I'm not an expert but apparently:
More weight + Less reps = wanting to gain more.
Less weight + More reps = wanting to tone more.
Start off by ignoring advice such as the above, it's a common myth that's perpetuated amongst magazines and the fitness community for some bizarre reason, despite having no scientific basis.
If you want to lose weight it's dead simple.
Calorie expenditure > Calorie intake
The exercise you do will determine what sort of weight you lose. If you don't do any strength/resistance training you'll lose both fat and muscle. By adding in resistance training you'll possibly even gain muscle whilst losing fat, as a complete beginner to weight training. (at least for a few months anyway)
When people say they want to lose weight they don't actually mean that for the most part (unless they're trying to qualify for some weight restricted event). Rather you want to reduce your bodyfat %.
If you're actually serious about doing something, then start making minor fixes to your diet for a start (so cut out random crap - replace standard drinks with their diet counterparts.. have an apple instead of a chocolate bar etc, try to eat more lean meats and increase your protein intake) and start going to the gym 3 days a week doing weight training. (Do anything, the important thing is you get into a routine of going to the gym several times a week)
Once you start getting into a good routine of actually going to the gym, start looking into proper routines you can do. I'd recommend Starting Strength or Stronglifts 5x5 for a beginner. If you're keeping your calorie intake down you'll soon start shifting some fat. Just keep going to the gym regularly and keep gradually improving your diet. Make minor changes to your habits, don't suddenly decide you want to go on a crash diet tomorrow & gym 7 days a week, ease yourself into it and you're far more likely to make changes you will stick to long term.
Just pick one change, and start at it tomorrow. So decide that this week you're going to start going to the gym on mon/wed/fri, doesn't even matter how long. Just stick to it. Once it's a solid part of your routine, start cutting back on a couple of dodgy foods you eat. Then look into the strength routines I mentioned above, etc.. Minor habit changes over months have drastic long term results.
I started off when I was ~17 going to the gym a couple days a week doing cardio and a crappy weight routine, by the time I was 20 I was taking things a lot more seriously, doing a proper strength routine (& lifting respectable numbers) and well over 40lbs lighter (~210lbs -> ~170lbs). That weight will never be coming back because I changed my lifestyle, rather than looking for a quick fix.