Am 270 lbs - 5ft 6 - and am 24 y/o

like you see am really fat, and I hate it, I really want to lose weight by September (my sister's wedding), I have seen the biggest loser want to do like them, but how can I motovate myself??

also the gym that is very close to my house is the same gym I used to go to when I was slimmer, so am shy to go and have people think I'v got so huge, what do you think??

any tips to get me started would be great help

thanks a lot