Scared about my finales?

Well im very good at reading. Im not to worried about that but the only three things im worried about is World studies, Algebra, And Environmental science. Im not sure what happens to my grade if i fail a final. but if i fail Four classes i will have to take the freshman year over. I have a D In worldstudies, And in science i have an A. But i know for a fact i not going to pass algebra ahh:( What should i do... And for Last semester i failed Algebra... If i fail 3 classes than i have to take my year all over again!!!