:17 in the this video
This exercise is pretty much the exact same set up as the standard Bench Press except you will position your hands much more narrow.
The position I like to get in is one where the hands are about an inch outside the chest when the bar is lowered down.
This close grip position is going to force you to keep your arms tight to the body and utilize the triceps much more.
This exercise is great for building those arms but also great for sports that require the use of your hands for blocking/maneuvering in close quarters (think football linemen).
Try creating the sensation like you're trying to bend or break the bar to increase the focus on the triceps even more.