you should have at that age at school covered reproduction and sex facts in biology etc.
15 is way to young to start having sex but many young immature females feel the need ot or wont be loved or liked ( they always regret in later life)
I wont give You any specific sites ot look at as they wil probably be regarded as porn and I don't wnt to get into trouble here. Ask your teacher to assist You here. or better still your mum.