Click on post reply
top line of menu is a paperclip icon - click on it.
A smaller box appears and the top line says 'upload file from your computer'.
I keep all my forum piccies in a folder on the desktop called Forum
Click on Browse, find the photo you want to upload, and then click (or double click depending on how you have set up your mouse settings) 'upload'
It may take a while depending on your connection speed.
Where it say 'uploading image' this will change to 'current attachments' when it is done.
Close the window.
Your piccie will appear as a thumbnail on the bottom of the post.
We then right mouse click the thumbnail and select the second option on the drop down list 'open link in a new tab' We will then see your piccie in all its glory
Hope this helps.