I personally believe all the stories that occurred in the bible. Obviously there are Jesus's parables which are made up stories to prove a point (hence the term parable). When it comes to things like how old the earth is and did God really create the universe in six days it is hard to say. The bible doesn't really give us any definitive time period for things and six days might be actual days (God is all powerful) or six ages it is all up for debate by theologians. My faith does not rely on knowing exactly how it happened but that it did happen is a supposed six days (depending on the definition on days).
Many of the other stories I do believe happened they way they are accounted in the Bible even if some are very hard to believe. But that is what faith is! Faith is believing even when there doesn't seem to be a lot of proof. I have never seen God, but I have felt his presence, I have heard words from him. I have heard of healings, experienced one myself. Heard of miracles in the modern day as unbelievable as those accounted in the Bible. So I don't need to know every detail of what is and isn't true because I have a God who has saved me, made me new and that is all I need.