The Carabiner Wrap is a major improvement on the "Suicide" method because the rope wraps around the carabiner and generates substantially more friction, which supports much of the rappeller's weight. The method only requires one carabiner, although a second one for attachment is desirable to keep the rope from rubbing against the seat harness. This is one reason that the method is popular in the military (they used it when I was in ROTC ages ago), but remember, the military functions on the principle of acceptable losses.
The rope is wrapped once (or less often, twice) around the carabiner spine, and braking is done against the hip. There has been quite a bit of discussion of the carabiner orientation, with the conclusion sometimes being "gate up and in." The photo shows a carabiner with the open end of the gate up and the hinge at the bottom. "In" means to orient the carabiner vertically with the gate toward the rappeller, with the idea that this position protects the gate from being opened accidentally. I prefer to keep the carabiner horizontal, with the gate up, and the rope oriented as shown. Notice that this arrangement directs the rope toward the braking hand (in this case, the right hand), and that the torque on the carabiner tends to rotate the gate towards my body. Naturally, I'd use a locking carabiner.
Do not use this method without a locking carabiner.