Don't let your fears drive you away from this church. In fact, God may have led you to this particular church so you can learn more about the Bible -- and about Him. The Bible urges us to "desire the pure milk of the word (of God), that you may grow thereby" (1 Peter 2:2, NKJV).
You may not know much about the Bible, but others in the group probably don't either, and a small group Bible study can be an excellent place to learn. In any case, don't be afraid to admit your lack of knowledge; those who take the Bible's message seriously won't want to embarrass you but help you. I hope you'll take this as a God-given opportunity, and enter into it with a sense of adventure and expectancy.
Even if you don't decide to join one of these groups right now, make it your goal to learn more about the Bible -- through sermons you hear, through gifted Bible teachers, and through your own reading of the Bible. The Bible is God's Word, given to us so we can come to know God and how much He loves us. Can you think of anything more important?
Don't be content to be a "pew-sitter" -- someone who just attends church but never allows God's Word to enter their hearts and change them. Instead, commit your lives to Jesus Christ, and then ask Him to help you "grow in the grace and knowledge of our Lord and Savior Jesus Christ" (2 Peter 3:18).