Wire colours vary slightly between different models but the basic setup is the same. Use the original wire sizes as a guide when choosing your new wire. If your battery is in the boot then you'll need to go to a larger cable to minimise voltage drop over the extra distance. There's a diagram below to help.

Main GND - These are the big black earth straps. They should go from battery -VE to the lug at the front RHS of the inlet manifold and to a good chassis ground point. Custom made from heavy battery cable for most conversions.

Starter +VE - (blk/red) Heavy battery cable from Batt +VE to Starter. If you've left your battery under the bonnet then a suitable length cable can usually be found with pre-crimped lugs at any of the larger auto parts stores. If it's in the boot then you'll need to source some suitable cable and have lugs crimped on.

Starter signal - (blk/w) Goes to the spade tab on the starter. Connects to IGN switch "start". You should be able to use the original wire from your car on here.

• Charge - (white on S13, blk/red on S14) This is the big lug on the alternator. Connect to Batt +VE (preferably via a large fuse - 80A)
• 12V Sense - (white on S13, yellow on S14) Smaller gauge wire. Connect to Batt +VE too. (preferably via a 10A fuse). This wire is used by the alternator to remotely sense battery voltage. Leaving it unconnected will cause the alternator to run "open loop" and charge at the maximum voltage. Not good for your battery!
• Alternator GND - (blk) With lug on each end. Connect from alternator body to chassis.
• Charge light - (w/red) Connect to charge light on dash. You should be able to use the original wire from your car here.

HERE'S a diagram of the alternator wiring (S14) courtesy of the ever helpful Mr. Nissan.

Oil light - (yell/blue) Connect to oil light on dash.

Neutral Switch - the rear most of the two switches on the right side of the gearbox. Not needed.

Reverse Switch - the front switch on the gearbox. Connect up to your reverse lights.