Hi, thanks for your feedback.
You simply add a CSS style selector to the RCOA block. If you want to apply it to all images just enter "img" in the "element" field. There are some screenshots at:
http://c5extras.com/add-ons/round-corners/...

If you want specific images, it will depend on how your theme is structured. The "content" block doesn't have any built-in class that you can select just those - but you can use the "design" feature in Concrete5 to apply a CSS "id" or "class" to any block, and use that as the "element" in the RCOA. For example ".mycontent img".

Hope this helps.

JB

Yes and know. I am unable to figure out what you mean by adding it to the CSS.

Concrete5 is built for super basic beginners, and although I understand some coding. I am unsure how to implement it.

I added the round block.
set the id to img.

but the rest I am unsure how to do.

Ok, I've recorded a new demonstration video and uploaded it to YouTube:
http://www.youtube.com/watch?v=lGKPsogVps8...
This shows to how add the rounded corners block and assign a CSS "ID" to existing blocks, as well as find the ID on elements from your template.

It's now been added to the C5 marketplace listing so it will help other C5 members.

Hope this helps.

JB