Step One:

To add art go to "Your Account" then "Manage Images" there you browse your computer and upload the image(s) you want, once it uploads properly it gives the correct code for the images you've uploaded.

Step Two:

Go to "Your Account" choose "Add New Story", read the submission rules, next choose category "Fan Art", fill in the Title, chapter title is the same as the Title, the Summary includes whatever description and this:

For contest art:

MdM Contest Entry<br><b>Size: --- x ---</b>
For regular art:
<b>Size: --- x ---</b>
the "--- x ---" is for the pixel size.

Try to keep art size under 800 x 800 pixels, otherwise people have to scroll to view your whole piece of artwork.

Next fill in the genre, rating, and warnings and finally the story text will be like this:

<center><img src="stories/AUTHOR#/images/FILE.EXT"></center>

You change this part: <img src="stories/AUTHOR#/images/FILE.EXT"> to the code you got in step one.
"Preview" check for errors then "Add Story".

Any questions, write Sapphire for help.