I know you'd like to be able to just stick them straight into your post but there aren't many forums which run without ads and allow this, so imgur is the way.
Go to.
www.imgur.com/upload
No need for an account.
When the page opens, drag in the pic or pics you want. Or “Browse” and select.
Give them time to load
When complete (you should get a little % readout at the bottom of the pic),

Move your pointer over the top RH corner of the photo and you’ll see this appear.

Click on the drop down arrow to see your options.

Select “Get Share Links”

Then pick the BBCode (Forums) options.
You’ll get this to paste onto the Realsurf post.

Done!