ok considering you have a aftermarket deck.
your gonna need to find a blue wire on the back of your deck this is your remote wire.
on the amp your gonna have power, rem, ground, also rca's
power, 4 guage is good for anything over 500watts run wire from battery woth a fuse within 12" from the batt. and run that down the left side of your interior.
rem= remote take this wire from the back of you rdeck and run this wire along with your power wire.
ground - get the same size wire as your power and ground this on you chassie some where, most people use the seat belts bolts, just make sure its no longer than 3 ft.
RCA's - these plug into the back of you deck but run thses down the other side of your interior (keep these away from power wires).
they sell amp wireing kits wit everything your gonna need, just buy one and take your time keep all wires orginazed and use lots of zip ties, the neater it is inthe begining the eaiser it is to upgrade or find problems.
good luck