Hey Jodie!
Do you have a plan in mind? We have a huge number of diet plans here, all with forums and information, so look around. You're sure to find a spot that'll work well.
You might also want to check out the 20-somethings, for people in your age range.
Wherever you decide to post (and I post ALL OVER, so you don't have to stick to one spot!), just jump on in and get going. You can do this!
Can't wait to get to know you better!