you remote wire is for turning the amp on..a switch really..it usually connects to some sort of power that is turned on(ex:igniton)but mostly they run from your head unit to the amp itself so when you turn your radio on the amp will follow...
if you have an aftermarket headunit, connect REM of the amp to REM or PWR ANT of the ehad unit. if this is a stock stereo, connect REM to a switched 12V igition line. this tells the amp to turn on and off with the car or the stereo.