Foods are given a pro points value worked out using the amount of protein, carbs, fat and fibre. In general foods higher in protein and fibre are lower in pro points value. Fruit and veg are zero points. You are allocated a daily points amount, 29 for the majority of people but some have more. There is also a pot of 49 weekly points which you can use as you want or not at all. Makes going out a bit easier. Plus you can earn points by exercising.
I have 30 points and today will go something along the lines of this:
Breakfast - slice of melon (0), 75g bacon (2), scrambled egg (2), Tomatoes and mushrooms (0). 250ml skim milk for tea during the day 2) Total 6
Lunch - 4 Ryvita crackerbread (2), 2 tbsp light Philadelphia (2), 30g smoked salmon (1), leek and potato soup (2) Total 7
Tea - 120g roast chicken (5), 200g potato (roasted in frylight, 4), 6g gravy granules (1), lots of veg, meringue nest (1), strawberries (0), 1tbsp WW thick cream (1). Total 12
That leaves me 5 points as I get 30. Not sure yet what I'll have.
You can have anything you want as long as you point it so other people's day will look very different.
There is an app for the iPhone which I use to track everything, it's very good and makes it very easy. There's also something for Android phones.