I dont know if i have the right size condom, its difficult to roll past the head and doesnt go to the base?

Several issues: If your penis is very large and thick, this could be an issue. Most condom issues are related to the way it is placed. Most condoms have a reservoir tip, so after opening squeeze the tip ( don't put on ) and see if it rolls downward. I suggest practicing on a banana or small cucumber. If this does not work it could be inside-out. If after trying these methods, try buying "magnum size"condoms .