Recumbent Exercise Bicycle

Hello everyone, yes, I realize I’m overweight. However, I’m sick of being fat, and would like to look and feel my best. I’ve had too many years of low self-esteem. I own a recumbent bicycle, as well as aerobic/pilates/yoga DVDs. What would be a good exercise routine (amount, etc) and diet for someone with flabby abs and developing cellulite? I’m tired of my out of shape body. I’d like to lose 50 lbs in 6 months or less, is this possible?!? Thanks to everyone!