Embarrassed to ask!!

I've always been a 2 channel music lover - happy with my left and right channel directional sound. It's time to "catch up" with the multi channel
surround sound concepts of today...
How do I go about adding channels to this configuration:
C5 or C4000t pre-amp, TFM45 and ALIII

Was thinking of adding a sub (AL's a little thin on bass) - how does one connect one up ??

Consider something like the DPL-33 "surround sound processor" I see them on EBay sometimes. Leave L and R alone, just add a sub, center rear L and R.