you have taken the first step Tan, admitting that you need to loose weight. I don't think it matters if you have to loose 2 kg or 20 kg's by admitting that you need to you are on the way. I personally had about 30kg's and am down to about 26 kg according to the BMI thingy.
I have started Weight watchers but what I have really done is cut down on all the crap. I don't have butter on my sandwhichs for instance and have switched to low/skim fat milk/cheese/yoghurt (while keeping the full fat for DS of course). It is a major hassel as it is more expensive but in the end if spending more $$ will help me loose weight then it is something for me and it just has to be done. Have in season fruit around, it is tastier and it is just as quick to grab a pear or banana as it is to get biscuits. Clear the house of chocolate and get some hot chocolate drinking powder for that chocolate hit. I have discovered corn thins which are great when you want that chip crunch, they are tastier then rice cakes as well.

As with anything it it has to be 1 step at a time, try and get to the park every 2nd to 3rd day and build it up to more often, take baby steps with your food and you will start to see some results (oh doesn't that sound easy wish it was that easy)