I've seen the books advertised second-hand on Ebay. If you want to learn how the plan works in any depth one option is to sign up for a couple of months to the Weight Watcher's website, or just check out their forum (you can check out most parts of the message boards for free).
Weight Watchers Website (Australian): http://www.weightwatchers.com.au/index.aspx
Their forum: http://www.weightwatchers.com.au/commun ... index.aspx
I went to WW a few years ago and successfully lost a few kilos on it. There are two plans you can follow, Points and No-Count. With Points you use your weight, age and height to figure out how many Points you can use per day. Then you have a list of foods with their point values in the books. Some veggies are point free so you can eat as much as you like. You have to be very careful that your portion sizes for any 'point' foods are correct, though, because it's very easy for them to creep up! Many people the Points system good because technically you can eat anything you like, you just have to balance it all out so you stay under your points allocation. So if you like cheesecake you can plan ahead so you can have it once or twice a week, but you'll have to minimise your points in other areas to do so.
The other plan is No-Count. On that one you have a huge list of 'good' food that you can eat at meals. You don't have to count points, you just have to make sure your portion sizes are sensible. You can have unlimited fruit and vegetables between meals as well. You have a number of points to use on treats per week and you can use them as you like, on sweets, alcohol or fatty food. A lot of people switch to this plan if they plateau on the Points plan, or if you prefer eating 'unlimited' healthy food rather than counting every single point. You need to be aware of your hunger signals to effectively follow this plan so it can be useful to do Points first so you get programmed with how big serving sizes should be.
Good luck! I hope it works out for you if you decide to do it. I found I couldn't really follow the plan on my own once I stopped attending the meetings. I needed the accountability of the meetings to make it work for me.