The question I've been asked. "Must I believe in a 6 day creation to be a Saved?" The answer is no. Jesus says in John, "For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life." - John 3:16
This is what you have to believe:
"That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation." - Romans 10:9-10
After you are saved and born again in the Spirit, God invites us to know Him and gain greater knowledge of who He is through the studying of His Word. The Holy Spirit will reveal things to your heart and mind which may lead to a change from your initial beliefs. With an open heart and open mind you may begin to believe in such things as "The Flood" in Genesis, "Adam and Eve", and the "six day creation." However they are not prerequisites for getting saved. So don't let these questions be a stumbling block that keeps you from trusting in Jesus as your Savior! We must remember, though we are created in His image, He is the Creator and His thoughts are higher than ours. (isaiah 55:8-9)
My prayer is that you will know Him today!