One of the best ways to add an image to a post is to set up an account with
Photobucket, or one of the other image hosting sites. Some folks will suggest ImageShack but I don't like that site because it tends to try and place a cookie on everyone's hard drive for every image posted. Not that big of a problem for me as I manage every cookie that comes my way (
most are blocked). It just ticks me off that they do that.
Anyway, upload your images to Photobucket (
details o how to post images on a forum are found at Photobucket) and use the Img BBCode button at the top of the text box when you're typing your message to post and place the link to your image in between the [img] tags.
For the sake of visitor connection speed, convert the png file format that is default for RW to a jpg format. png's are pretty big files and those on slower connections will have to wait while those things load in the post.