3 of my tone knobs are snapped off at the pots, I need to know how to go about finding replacement pots and how to install them myself.
Not an expert here but I'll give you a bump.

Try googling 'amp potentiometers'

Also, I know Weber carries stuff like this:

As far as replacing, you may need to seek some more help with that. Basically, after making sure the amp is discharged of voltage (not necessary on solid state amps IIRC), you would de-solder the connections and keep close track of what wire goes where. Then replace and solder wires back on. There may be more to it than that. Like I said - this is more of bump.

Did the whole post snap off or just the plastic knob?
It was the whole post. I'll check out that site. I just want to educate myself about how to do it myself, because I don't feel like paying 60 dollars to fix a 100 dollar head.