Stan, I use photobucket.com, a free service, to upload images. Each image has its own page that you can link to. Once they are uploaded, simply cut and paste the URL that web site provides. Then add it to this message box like this:

[ pic ] the URL [ /pic ]

Don't place spaces before and after the words inside the brackets like I just did. Can't help with image size, but this is how I add all my images such as below:

I hope this helps,
Steve