You are given a daily porpoint limit based on your weight height gender and age. you must use them throughout the day. You also get a weekly 49 propoints to use however/whenever you want during the week, you dont need to use all these if your dont want to.
Majority of foods have propoints with the exception of most fruit and veg which are zero (some have points such as peas, potatos, sweetcorn etc), you can calculate the propoints of foods using a calculator or you can get an app for your smartphone, the pointpoints are based on Protein, Carbs, fat and fibre.
Hope this helps if you have any more questions please ask