How to edit texture files!?!

Hello there!
What program do I need to edit the scenery (bmp) texture files. Is there a certain program you need, or a special way you must open files to be able to edit them.
I have paintbrush (obviously), Photoshop7, Fireworks. Is it possible with any of these!
Thankyou!
ROBERTO
Slovenia!
What program do I need to edit the scenery (bmp) texture files. Is there a certain program you need, or a special way you must open files to be able to edit them.
I have paintbrush (obviously), Photoshop7, Fireworks. Is it possible with any of these!
Thankyou!
ROBERTO
Slovenia!