Hey Tasty,
First off, you dont burn the fat on your thighs by training them. You cant "point-burn" the fat. Fat is dissolved into smaller molecules from where the body chooses (if you eat less cals than you burn, that is), enters the bloodstream and is then used where needed. It doesnt "magically pass through to the muscle beneath".
Toning up can be achieved by working weights, and working weights is also an important part of maintaining muscle mass while loosing weight.
The weight-loss comes from eating smarter with less energy intake and burning more calories through cardio-training.
For your specific toning questions, I would normally go into details about your lifestyle, work, health issues, training experience and such, but just off the top of my head, I would on the assumption that you are a beginner recommend seated leg press and leg curl each at 12 repetitions for 3 sets with a 1 minute pause between sets as part of a full-body beginner program. Talk to an instructor at your local health club and let him get you started on a specific program and let him teach you some basic workout technique. Training is not just theory, you have to see and try it first.
Good luck!
