Well that is easy. Just follow this procedure that I wrote up for OPs like you.
1. Create your account at http://photobucket.com/ - real easy
2. Use the folder with your name on it or create a subfolder (recommended). You do that on the left side where it says "New Album" > Save
3.Go to "Upload Images and Videos", somewhere in the middle. Now click on "Choose Files". This will most likely bring up your "Pictures" folder (but you can select another folder). Double click on the file you want to upload. After a few seconds you will see it. Now single click on your picture. On top of the picture you will see “Resize”. The best size to pick is 640X480.
4. If you want to post this picture directly on the Forum, click on IMG Code (last link), then right click on that and COPY. If you only want to post the link to the picture, click on Direct link, then right click and COPY. Then you got it in your clipboard (from where you Paste).
5. Now you can paste this into your posting. If you chose IMG, the picture will only show up AFTER you posted. In the posting you will only see the link. If you chose "Direct link", it will just be a link.