I'm not certain if this is the correct place to post this, but...

I'm having a problem with custom or home made brushes in GIMP 2.6

Specifically I downloaded a bunch of PNG files from RPGMapShare. These are all buildings. What I want to do is make each of these PNG files in to a building brush in GIMP for making district scale city maps. I can make the brush, no problem, but.. its read only. Can't copy it. So I tried saving to a different folder. Read only. I tried the "documents and settings" brushes folder. Read only. I tried the "my documents" brushes folder. read only. All I want to do is rotate the damn things... No matter where I save them, read only. I've changed attributes on the files, the folders, in Windows XP and in GIMP and no matter what I do... read only!!!!

Gaaah!!! The time I've spent on this I could have drawn 12 maps with a pencil and I'd probably not be wanting to pull out my hair.... but this is for a VTT game.

I've googled "gimp brush making" "brush editing" ... I'm lost. I got no idea what to do now and I know its something easy that I'm over looking and.. help please.