I need tips please help?

I'm a twelve year old girl and I sweat, ALOT. I need tips to at least hide my pit stains until this 'puberty' thing is over. Also what deodorant/ antiperspirant would work most effectively? Any advice is appreciated thanks in advance. (here is a pic of how bad my stains are after 2 hrs) a href="http://s592.photobucket.com/albums/tt3/shelly-mack/?action=view¤t=Picture142.jpg" rel="nofollow"http://s592.photobucket.com/albums/tt3/s…/a