well if this is for the vegas regal winning screenshot contest-then go to that thread and click the link in bels post to start your thread,
beneath the preview buttons there are 2 boxes -check the box that says attach file(s) a file upload will open beneath that when you do > click the browse button > select the file you have saved in paint > scroll down and click upload file(s)
when it is done uploading Attached: screen shot posting.JPG [remove] [insert]
beneath the box you checked - click insert to put the shot in you post