I highly highly recommend a personal trainer if you do not know much about working out, lifting, and exercising in general. A lot of people make the mistake of assuming cardio is the way to lose weight, which is far from the truth.
The best way to lose weight is diet change, and resistance training, along with cardio.
I weigh 215 pounds, 6ft tall, and I bench press 425 pounds. I am fit, have a 6 pack, and girls love it. But I will tell you one thing, I started off young. At age 15, but not until I was maybe 21 did I begin to see great results. That is because it took that long to learn things, the methods, how to do things right, etc.
Follow a routine laid out by a personal trainer.
The best results from a work out routine can be given by a PT. They are there coaching you, pushing you, and they get a feel for you and your body.