Getting a group of girls together to do the workouts is a good idea. It's actually a great for motivation. You might need to adjust the workouts a bit, but that's OK. The most important thing is that you get the exercise.
As far as diet is concerned...why not give the Fat X diet a try? The principles of the diet are pretty simple, surround yourself with nutritious food and try to minimize your exposure to "junk" food. Start with those small steps and then you can adjust from there. As I've written in the past, most people fail long term because they try too many changes, too fast.
There could be a few reason why you're getting dizzy on the treadmill. It could be lack of nutrition, fitness level, or just the change from moving on an object and then getting off that object.
As far weight loss being more difficult for women than men, check out the Diet Like a Man video.