Have you read the manual on this? Custom BB Codes Basically, you may have two 'options' for your bbcode - a param and an option. That should do for your two blue items.
Yes, I have done exactly that, replacing the URL with {param} and the image description with {option}, but I cannot get the option portion to work, but I think I'm not sure what to expect from the option code either. Is that supposed to provide a pop-up to type text into?
This is what I have entered into the Replacement section
Code:
<img src="{param}" align left hspace=10 alt="{option}">
and I have option turned on.
All I get in return is the image url between the BBCode options.