WHAT TO WEAR! HELP ME!

Hi. I was invited to my friend`s Quinceanera. I haven`t talked to her for about 2 years since I moved. I have no spanish background or knowledge of how any of this works, but I want to go to see my friend again, and of course celebrate.
What do I wear??
Do i give her a present??
Do I wear separate outfits for the church ceremony and the party??
And if there`s any advice you could give me, please do.

Im 13 if that makes a difference in anything. Please help, cause Im absolutly clueless!!!!

Thanks, Christine
P.S. Its this sat. So respond ASAP!!!!!!