I wouldn't recommend dating at such a young age but if you really wish too try going outside and meet new people. Always remember to be yourself! Online dating isn't such a great idea because you're never really sure who is that person on the other side of the screen. Hope this helps!
If u are already resorting to dating sites which match you up with a guy/girl (I'm not judging) at 13 because u don't have time between gym and nap time to talk to a girl/boy (again, not judging) and talk to them in person than you have a loooooong ways to go my friend. In all seriously tho, find a girl/guy u like and if u feel more comfortable on the computer than add them on msn or Facebook. In any case, face-to-face interactions are kind of a must for dating. Sorry to burst ur bubble buddy.