GIRLS PLZ HELP!!! why is she mad at me?

You're acting way to fast...she probably thinks you are taking things to fast when you just told her you liked her. Leave her alone for a bit, let her take some time to see what it's like when you aren't constantly trying to get her attention, it might attract her more. But the constant nagging is an instant turn off. Give her some time and she'll come around, just don't rush anything. If she continues to ignore you even if you've given her a break, she might just not be interested, and f thats the case, let it be.