When you push a button on your keyboard, the key goes down, a metal strip on the back of the key bridges a gap in a circuit. It's set up so that each key activates a different circuit, each circuit sends a specific signal to the processor, so you get letters. Obviously, since you don't have fingers you must use plasma arcs from your solar-flar-ness to bridge those gaps instead of metal contacts.
*nods and pretends to understand* So how do you type? You look rather old. Your fingers must be really fragile and delicate. You shouldn't type too much.
The smoke is purple because I like a little variety once in awhile... grey smoke gets so boring, don't you think? *shoots out battalion of green smoke rings* And my smoking isn't bad for me, because I use my magic to block it from settling in my lungs.