Hi...
I'm fairly new the the boards too but have found that everyone has been very helpful. As was recommended to me, really check what you are eating, diet is the most important thing in getting your metabolism moving. There are a ton of "boosters" out there ie; xenadrine, diet fuel, stacker, but I would recommend concentrating on your diet and incorporating some weight training along with your walks. If you begin to write down everything you eat, it will be easier to find where the culprit lies. In my case, I found out that even though what I was eating was healthy, it was clearly not proportionate in terms of protein, fats, and carbs nor was it enough!
I read a really inspiration story that sweethunny posted that you may want to check out on the diet discussion board. She shows her before and after pics and you can see how her hard work has paid off.