All you need to do, is calculate your daily caloric expenditure (by using a calorie calculator.. Google it) and then depending on how much you want to lose per week (up to 2lb, more is considered unhealthy) and then subtract the appropriate amount of calories from your daily intake.
So for example, if your calorie maintenance was 3000 calories, and you wanted to lose 1lb per week, then you would eat 2500 calories per day, leaving you with a 3500 calories deficit at the end of 7 days. This would result in a 1lb loss of fat as there are 3500 calories in 1lb of fat.
Now, cardio isn't even required when trying to lose weight, it's all about diet, all cardio does is burn extra calories so you can eat a little more, so unless you genuinely want to get fit, you don't need to do it.
Weight training is what you should be doing, because when people lose weight, if they don't train their muscles, it's possible to lose a lot of muscle so after you've lost a lot of weight, you can end up being really small as you've lost a lot of muscle too!
Hope this helps..
