The blocks with cleats shackle to the car on the jib tracks. The small single blocks (there should be two) are to be attached to the clew of the jib; a simple way is to tie one to each end of a small-diameter yet strong line, push the center of the line through the eye or grommet in the jib, then drop both blocks through the loop. The jib sheet is tied to the becket on the bottom block, runs thru the single block, then back to the bottom block, around it, and out thru the cleat. The other side has to be rigged the other way around, but make them alike. This will give you your 2:1 purchase on the jib.

Oh: The cleats on the mast are part of the downhaul system. There should be two double blocks on the tack of the mainsail; if so, the downhaul line will run in thru the cleat, up around the outer sheave of the double, down around the outer sheave of the triple on the boom, around the inner sheave of the double, around the middle sheave of the triple, and duplicate on the other side. It looks like a 6:1 purchase, probably fine for a 16' boat.

good luck, and post back how it all works..