Top says all!!!
If you have to ask, then clearly you're too young. Wait until you're out of H.S. and at least in college. Then find someone who has a steady job, get married and then this "SEX" thing will come natural to you.. believe me! For now, focus on your school work and hanging out with friends.
when a mans penis enters a womans vagina. then they bouce up and down.. haha and the guy erects into the women. then she can get prego becaue of htat. then the man withdrawls. then he enters again. etc.