The left arrow is where either the maf or tps should hook up. See that other little black circle thing on the back with two screws holding it on? It's circled on top in this pic, and they should look exactly alike. I forget which one is which, but I know the engine should have one of each! I'm assuming the tps is what he's missing since it's right next to the throttle cable.
The capped off thing is for a ~6" vacuum line that goes straight into the back of the engine. Is there another capped off hole on the block back there? It would also help if you told us what kind of engine he has.