For general posting guidelines see the sections in Help (top right corner) - Posting a New Thread and Posting a Reply.

Posting Images: Before posting an image in this section think about the reason.

If it is a graphic for editing advice:
- Use the New Attachment Option at the bottom of the editor window for jpegs, pngs. If the image is reasonably small, insert it into the post.
   

- Attach a Gimp compressed image file, file.xcfgz.  The maximum file size is 2MB. Using a development version of Gimp? Enable the maximum compatibility option. 

- Larger images are best placed on a storage site such as http://www.dropbox.com for downloading. Make sure the file is in a public folder or marked for sharing. Include a link in the post.


If it is a problem with using Gimp
 - A screenshot is often better than a long description. 
Gimp has a built in screenshot tool. Find it in File -> Create -> Screenshot.
 
- Attach the screenshot as above, but consider

A screenshot of the canvas, gives no/little useful information
   

A screenshot of the whole desktop, a waste of space 
   

Edit the screenshot but include as much relevant information as possible, tools, layers, active brushes, fonts etc.
   

Looking forward to all those Gimped images
   

http://www.smbc-comics.com/comic/punishment