Right, after looking through various posts on here and failing to upload photos successfully, I have been through quite an extensive process of trial and error.. I have now managed to post photos reasonably simply using a method that's not too dissimilar to the one above - suggested by admin. I'll try and explain it point by point the best that I can. I hope it works for you!
1. Upload your photograph to Flikr
2. Keeping your Flikr page open on a separate tab, go to My Garden forums and select the area of the forum that you want to post within or the message that you’d like to reply to
3. Enter your topic in the subject field and compose your message
4. When that’s complete, select the options tab
5. Click on add/update the click on the radio button 'Link to URL’
6. Go back to Flikr and open up the photo that you want to include
7. Right click on the photo and a little box should come up ‘view all sizes’ – click on the 'Medium 500' option
8. Now right click again on the photo and select ‘Copy image URL’
9. Go back to your My Garden forum post and right click in the ‘Link to URL’ box
10. Select paste. The URL should now be pasted into that box
11. Click save
12. You should then be returned to the options page (with all the smiley face icons)
13. Click on ‘Post’
14. You’re done!