Actually, I think the other replies might be completely confusing
depending on what kind of roof you have.

Do you have sort of the classic american monopoly house "two slanted
pieces meeting in a ridge at the top" roof, a so called "gable roof"?
If so, then listen to the other replies. It just comes down to cutting
a bunch of shingles in thirds, then laying the pieces out like a big
caterpillar right down the ridge so that only the nice part of each
piece is showing. The Very last one you can cut off the ugly part. You
end up with 4 nails showing on that very last piece. This method works
basically the same if you have a ridge vent, too.

Or, do you have a very simple "one slanted piece" kind of roof,
basically just half of a gable roof, which is called a "shed roof"? If
so then the caterpillar trick doesn't work, since there is nothing on
the other side of the peak. In this case, shingle right up to the very
top edge. Hopefully your last row will have the visible ugly part
butting right up against the top edge. Or even better, it will hang
over a bit, and you can trim it so that it fits exactly. Now nail your
piece of drip edge on so that it sits on *top* of that ugly part -- the
rain landing on the drip edge will either fall off the one side of the
roof, or run down on top of the ugly part of the top row of shingles.
Then, cut off the ugly part of an entire row of shingles, so all you
have left is the nice looking tabs. Just nail these across the top edge
of the roof, *over* the drip edge, and preferably hanging over a little
bit off the top edge of the roof, so the entire drip edge is not
visible from above and won't get rained on. These should cover up all
the ugly part that was still visible from the row before. You will end
up with a row or two of exposed nails holding on these last pieces.
Just put a dab of black roof cement on each nail head, and no one will
ever notice.

-Kevin