If it's in a post, when you click the button to post, near the bottom of your message, directly above the SUBMIT buttion is a little area that says ATTACH FILE. You use the browse buttom to find to search your computer for the file. In that little area it also includes the valid file extensions: gif jpg png txt zip bmp jpeg psd jsc
If it is anything other than those, it won't upload.
If you were talking about just posting a picture in your message and not attaching it, just used the IMG code located above where you type your message, you'll need an ADDRESS/URL of the picture. Hope I helped. :hatsoff: