You have your dailies for just general everyday eating, your 49 weeklies can be used how you like in addition to your dailies. For example if you have a meal out on a Saturday you could have your usual daily points and then make up the difference out of your weeklies. I use mine for treats at the weekend, other people add 7 additional points to their daily allowance. They are great because they mean if you have a cheat you are still sticking to the diet.
Hope this helped.