How do you post these on the forums

Do you mean images? If you do, here's how:

Go to ImageShack and upload your image. You will get a few links. Pick either the one that says "Hotlink for forums" or "Thumbnail for forums." Copy that one, and paste it into your post. Your image will be displayed once you post.

If you want to learn how to edit RuneScape images, look at some other people's edits and try to learn from them. You can also look at the stickied tutorials at the top, and search around.

Actually, using the hotlink results in a link to Imageshack doesn't it? 'Direct link to image' would be a better option..

We can assume you mean pictures, but it would be better if you told us what "these" are.