If you do not believe in the Bible, how do you know what God wants you to do?
You got to be kidding me, right?
It's pretty obvious. Look back on your life. Do you not see God trying to let you know what to do? Like most of us, you didn't listen at the time, but in retrospect, you see it now.
Look at a tree, or a flower, or a sunset, and you see God.
No book needed. It's right there in front of you, everyday.
Perhaps you need guidance from some 2000 year old book, or from self-professed expert guides (priests, etc). I don't.