how can I tell when im horny? what happens?
Hmm. I think it differs for different people because we all have different turn ons.
I guess if you start thinking about sex, and imagining the feeling?
Or if your vaginal area becomes wet; although this may not always mean you are horny.
Usually, when you're horny, you feel really hot between your legs, and sometimes you wet. However, being wet doesn't ALWAYS mean you're horny. It usually just means that your body is cleaning out your vagina.
It depend on that to whom you want to tell this.