The only ones that can change the forum permissions would be the forum Administrators (those with administrative privileges). Think Sapience or higher. They have the permissions set as they are with good reason. They are not going to be changed without good reason, either.
What you need to do is upload your images to an image-hosting website and then link to it. Click on the IMG in the IMG code is On in the Posting Permissions section below to find out how to use the tag.
"Everyone's got one. Better to be a smart one than a dumb one." - me
"It's people like you that [I]think[/I] you know everything that give those of us that [I]do[/I] a bad name." - me
"Eat, drink, and be Merry, 'cause Pippin was a fool of a Took."