Any computer imaging software will do. Adobe photoshop? (But it is kinda of expensive) You can even use Paint or Microsoft Word.... Can also try free software like Deep Paint.
Can try printing at a few printing shops at Coronation Plaza or Peace Centre.
You should use either Adobe Illustrator + Photoshop or, a more user friendly one would be Ulead Photo Deluxe. If using adobe, u can dl brush sets. Illustrator is good if u haf someone who can draw on a tablet / using a mouse.