Hi Lily Rose,
If you want to know what sort of exercise is best then I can probably help. I'll give you general info and, if you want more detail, specific to YOU then I will try to help.
Firstly, this is what I do for a living, so I do know what I am talking about. If you combine the nitty gritty details I give you with the personal experiences you'll find on this site, you'll soon find a way of working that suits you just fine!
To lose weight you need to rebalance your food and exercise amounts. You need to burn off more calories than you eat. This is weght loss at its most simple (ha ha!).
What sort of exercise? Any!!! Do what you like, that way you'll stand a better chance of doing more of it more often. But a combination of both aerobic and resistance work is best. This way you get to 'burn off' thise calories and condition you heart and lungs AND you get to increase you muscle mass and therefore burn more calories even when you are sitting down!
How often? Well start off slowly. Stay commited to what you can do easily. Don't start off promising to do 1/2 hour a day, every day - you'll never make it, and every time you miss a session you'll feel bad. Try 1 or 2 times a week, then build it up!
How hard? Not very - no pain no gain, NOT REALLY. You will experience some discomfort, especially if you haven't done much exercise of the past few years. Your body and brain need time to adjust. But you should work at a level that leaves you able to talk, and a little warmer than you started. That's it. As you get fitter your body will let you know how much more it can do.
I hope that helped a bit. If I carry on writing I'll finish the book - sorry!
Get back to me if you want more info.