Uploading an image to a forum post is super easy. Just follow these steps once you've started your new message post:
1) Click on the "Insert Image" link at the top of the message window
2) Browse to the image on your computer (or link to an image somewhere else on the Web)
3) Select the "medium" image size
4) Add a description for the image if you want, but it's not required
5) Hit "Insert Image"
Voila! You're done.
The medium image size works best; otherwise the pic is so small you can't see the details or so huge you can't see the whole image on the screen in a single view.
Now let's see those wonderful watches!
P.S. I've added an "About this watch. . ." forum specifically designed for discussing questions about particular watches. Feel free to post your watch and see what folks have to say about it.