PhpBB3 BBCodes

I guess you caught my backup plan post on phpBB.com
'i want to change the corner image and remove the border top and bottom.'

Hi, I need a way to achieve rounded corners on the forum boxes (not category boxes, those are round by default), using images (so it's cross-browser supported)
I'm sure it's really simple but I'm a complete noob.

Hi, I know all mods are based on prosilver foremost, right? Is there any 'problems' with prosilver_se, or would all mods that work for prosilver automatically (through autoMOD) work without code-finding errors in prosilver_se? What other good styles are completely or near-completely compatible with ...