Thank you, notdecieved and $teve (how did You manage that?!) for Your answers!
But, I still can't get it right.
When I klick on the Image button, a little "Insert Image" window pops up. The background from the "Reply to Thread" window is then very pale. In this little window I can select "From Computer" or "From URL". I click on "From Computer" and then "Add an image from your computer". After it I select the picture from my computer, but I never get
[IMG] [/IMG] tags, always attachment tags:
Attach=config]3620[/attach]
I have no problems with inserting images from my computer in my e-mails or at ebay web forms, but that's too deep for me. Maybe I am too old or dimwitted.
P.S. To make sure, I always use the preview button before I send any reply.