How would I make an RPG that has girl stuff in it too? The only kids around where I live are girls, so I need to create one that will make it enjoyable for girls.

You'd be surprised as to the lack of difference between girls and boys. I'm a woman, but I've always loved video games, RPGs, and other "boy" things. Make a game with cool content that is presented clearly, but make sure to treat female characters with the same consideration and dignity that you would give male characters. Avoid using girls as plot devices or rewards, such as a damsel in distress or a princess to marry, and make sure that female characters can shine as much as male ones in all aspects of the game. In short, be respectful, and you should be fine.