In the New Testament a person is automatically "added" to the church as a result of becoming a Christian (Acts 2: 41). This is hardly surprising. "The church" in the New Testament after all is simply the body of believers. You become a believer, you become a member of the body.
You can't "choose a church" because there is only ONE church according to the scriptures: Christ's church (Matt 16:18). You're either in it or your not.
So, here's how it works according to the New Testament:
You hear the gospel
You believe in Jesus
You repent of your sins
You are baptized for the forgiveness of your sins
You are added to THE church, Christ's church, the church of God, the body of believers, the saved, those having eternal life
To see all these steps happening in one place at one time read the account of the very first group of converts becoming Christians and being added to the church in Acts 2: 36-41.
Notice the next few verses too (Acts 2: 42-46). The new believers continue on from there as a group, meeting together to pray, break bread, learn the apostles' teachings and so on. In other words, they were now "the church" doing what "the church" does.
And finally there it is again in v47: as others believe and join they too are described as being "added" to the number "by the Lord". Its automatic. Its not something you choose after becoming a Christian. Its something that is a by-product of becoming a Christian.
Wonderfully simple and logical isn't it? Much better than the convoluted ways typical of so much man-made religion. But that shouldn't surprise us either. It is, after all, God's way.