Does anyone know how i should hook up a pair of peavey sp118 Bxsubs with a pair of peavey pr15 tops and the behringer inuke nu6000 please help

You will require 4 heavy gauge 1/4" speaker cables in order to connect all 4 cabinets to the Behringer power amp. Usually two longer ones from the power amp to the sub woofer cabs. Then two short ones from the second "thru" jack to the upper 15" cabs. Remember the entire audio frequency range is going to all four speakers. Sometimes you will have problems balancing the low frequency levels between all four cabs depending on the loading of each. A more desirable way to do this is with a bi-amped arrangement. This way two seprate amps are used for the subs and 15" cabs and you control them independantly.