Hello Peter I'll jump in.
You will need a photo editor to size them small enough for posting on the forum. Some printer programs will have that feature. I personally like Paint.NET Just do a search for it as I wrote it here. It is a free program and if you aren't into all the bells and whistles of the fancier programs it's pretty straight forward to use. I'm sure others will make their suggestions for their favorites like Gimp and Inkscape. Which I can only say they were a little too involved for me to get comfortable with and I didn't want to take a lot of time learning how to use them. If it's simple enough for a dummy like me just about anyone can do it. When you get ready to post it to the forum click on "Additional Options" at the bottom left of the message you are posting, and you will see a line that says "Attach" followed by "Browse" which will let you down load any photo sized 128 KB, you can upload 4 of that size per post. If you have need of further assistence give a shout and someone will come to your rescue.
I hope this helps,
Gabby
