Welcome to the forum. Hope you are enjoying the Compact. Here
is the manual for the Voicelive 2.
Your guitar should plug into the Voicelive Guitar IN and then run from guitar THRU to the guitar input of the Compact.
Your vocal mic will plug into the XLR input,#1 on the rear panel in the manual, and then the Left or Mono output to the Channel 1 input on the Compact.
You control the mix of lead vocal, harmony vocal(s) and guitar by setting mix levels on the Voicelive control front panel section #8 in the manual.
Too much effects in the mix can cause or contribute to feedback problems, use sparingly.
You might like to completely eliminate the guitar from the Voicelive mix except for special tunes. The cleaner the sound the easier it is to work with and less confusion in trying to solve little problems that may arise.
Does this help?