I know first-order logic, but I don't know prolog. I'm just guessing the :- represents implication, i.e. ->, or it might represent the <-> operator. Commas likely represent AND, i.e. a symbol I can't post in HTML. 3 and 4 are universal statements, so you need the upside-down A universal quanifier symbol. So for example

FORALL P,S,X sister(X,S) -> female(S) AND parent(S,P) AND parent(X,P) AND NOT X == S.

Replacing the words in caps with the appropriate symbols. Don't know if that helps, or if you still even need help.