What does it mean to "worship God" to Christians in general?

The Trinity seems pretty simple to me. It is all God, just in three different forms. Father, God in His ultimate form. Spirit, God in the spirit form (can be in multiple places at once). Son, God in human form (Jesus Christ).

Well, I think, that in general Christians pray to Jesus Christ, to ὁ λόγος, because actually He is the only One Whom we (I mean humanity in general) saw when we are talking about the God. As I understand, the humanity have an ability of the communion with God only
owing to Jesus Christ, the Word:

Joh 1:1-3 In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by him; and without him was not any thing made that was made.

Furthermore, when Christians paint the icon of God, they picture human look of Man Jesus Christ, as it was remembered by his disciples.

Of course, when Christians are thinking about Jesus Christ and praying to Him, they think about Him, that He is God, not "some of the several gods".

There are groups within Christianity which focus on praying to the Trinity itself, then there are groups which pray to individual members of the Trinity and some groups which pray to only the Father.

Joh 16:23 And in that day ye shall ask me nothing. Verily, verily, I say unto you, Whatsoever ye shall ask the Father in my name, he will give it you. Joh 16:24 Hitherto have ye asked nothing in my name: ask, and ye shall receive, that your joy may be full.

Act 7:59 And they stoned Stephen, calling upon God, and saying, Lord Jesus, receive my spirit.

Eph 3:14 For this cause I bow my knees unto the Father of our Lord Jesus Christ,

I might speak to Jesus or the Holy Spirit but I only pray to the Father in Jesus name. I don't condone those who pray to either Jesus or the Holy Spirit or the trinity as a whole I just see no outline in scripture for such prayers. When I pray to the Father I just talk making requests and worshiping. In my mind I'm trying to think of things which would make my prayer acceptable and faith filled like a scripture or a positive confession. The theme of most of my private and public prayers are I love you and Lord help.

Prayer to me is what I do for love of God. I think about God's teaching, and I talk about it sometimes to God, sometimes to brethren. Prayer is to make God the focus and center of your own life. Jesus taught his disciples to avoid public displays and to go within themselves to communicate what they needed from God. He also taught that anyone must ask God for whatever they want, and to do it in earnest, nothing wavering and to demand from God what God has promised to his children. There are many parables about this behavior. Communication with God is non-verbal. It must come from your spirit to the Spirit of God, which as Jesus said "is within you." My experience is that God can read my mind. God is always present with me.

The trinity is a Catholic concept of God, which was dreamt up in AD 325 by a committee which included some 300 Bishops of Constantine's Greek Empire. It was a formula to squelch the teachings of errant Bishops and especially Gnostic Bishops. All Bishops had to sign a document we call the Nicene Creed, or lose their Bishopric, their property and pensions. Only six refused to sign. The Creed was full of loopholes and Bishops went their merry way and interpreted it as they saw fit. The Creed was revised twice more to fill in the loopholes. It was never considered to be the truth about God, but was the best the Bishops could come up with. The Church made it a requirement to accept this Creed before anyone could join the Church. So it is essentially a membership rule to be sworn to in order to be a Roman Catholic - the Greek Orthodox use a different Creed. It does not describe the truth about God which can never be understood by mortal man.

It depends on the denomination and their doctrines.

1. Some pray to the Father, sometimes calling him "Abba".
2. Some who are not able to believe in the Trinity usually pray to Jesus alone. Even some who accept Trinity also pray to Jesus alone because Jesus is the center of Christian faith.
3. Sometimes a specific prayer is directed to the Holy Spirit to invite Him to come and fill us so that we may experience the power of God.

Case 1 and 2 is the most common. Case 3 is very specific and practiced only by those who believe in the power of Holy Spirit. To a Christian who believe in the Trinity, it's all the same whether you pray to the Father, the Son or the Holy Spirit because they are ONE.

In the Nicene Creed, one of the oldest formulations of the Faith, and one which is repeated every Sunday by a large portion of Christianity, it says of the Holy Spirit:

I believe in the Holy Spirit, ... who with the Father and the Son together is worshiped and glorified, who spake by the prophets

In theory then, all three members of the Trinity are worshipped and glorified equally.

That said, your question specifically asks for practice, not theological formulation. And, since the Trinity is a hard concept to grok, one should expect significant deviation in practice. That being said, both in my Baptistic and Episcopalian circles, it is not all uncommon to begin a prayer with "Father God Almighty" (I do) and to end with "All these things we pray in Jesus' name." That one should so easily morph from one to the other speaks to the fuzziness of the distinction in our minds.

When discussing the role/s of the Godhead, study leads us to separate the individual persons of the godhead. Reduction is a useful thing in study - that's why we dissect things. That said, when you cut something up, sometimes you kill it :) I say that to say that my formulation of prayer (again, not uncommon) shows how we can dissect the roles, but still see the sum "Three-In-One" as one being.

Mormons and other non-Trinitarians (a very small percentage of Christians) very clearly believe God the Father and God the Son to be two separate people - but those of us who are Trinitarian tend to be a little wibbly-wobbly on the whole thing. In practice, we have a lot of bi-natarian theology (God the Father zaps you, and Jesus' blood saves you. That Holy Spirit Guy? Only Pentecostals and charismatics even know who he is!) - but even there, most Christians realize that Jesus is correct when he says "I and the Father are One."

I can only speak for me when I pray - I see the two fuzzily morphing in and out of oneness together - but I suspect that fuzziness is pretty common.