Right..........theres 2 thick red wires, and a thin blue.

Both of the red wires do the same job, they are just doubled up because theres big currents flowing across them. Both the reds go on the big thread on the back of the alternator, and the other ends on the main battery feed to the starter.

Thin blue goes on the small thread on the alternator!

FOR GODS SAKE remember to disconnect the negative side of the battery first though or there will be sparls flying