Lol. I thought you said you'd worked with computers for 30 years.
Find an image anywhere online (it needs to be online, not from your own pc).
Right click - press copy (or control+c)
Come back to your forum thread
Right click - press paste (or control+v)
It will work for your Ebay listings too, meaning you save money on galleries. Note: It won't work on 'all' forums, so on those that don't accept the paste, right click on the image, and choose properties if using Internet explorer. Then copy the url in the properties, click the image icon above your post editor, and paste it in the pop up box (or just add the image tags yourself).