I'm sorta new here, sooo... I was wondering can I make an rpg or adult rpg about anything I want? Like make a story about a werewolf or a story about the future?
In the Sexual Roleplay forum, yes. Or the Online Roleplay forum if you don't want it to be sexual or at least not mainly sexual.
However, if you have never made a roleplay before, especially if you don't have online roleplaying experience at all, you should look at how other people start theirs and participate in someone else's first. Werewolf rpgs for example are pretty common, you could probably find a public one to join.