I've upgraded the software to now automatically resize images and simplified the process, here's what you do:
1) Click on New Topic or Post Reply
2) Click on Upload attachment

3) Click on Browse

4) Then locate the image on your computer and click 'Open'.
5) Click on the button 'Add the file'

6) That's it. When you've finished your message click on 'Submit'
When viewing these images within the Forum you can click on them to view them in their full size - then click on the photo again to return to normal.
Now, let's see some new photos, eh?