What are some exercises i can do with dumbbells to work my triceps?

Bent arm extensions: Various positions allow for resisted arm extensions with use of a barbell. You can sit (picture), stand, kneel, or lie flat on a bench to name a few.

Triceps.: Dumbbell exercises for the triceps include sitting overhead triceps extensions (either with one heavy dumbbell raised overhead with both hands or two lighter dumbbells - one in each hand), dumbbell kickbacks (light weight) and cross-body triceps raises (done lying down with elbow straight in the air - extend dumbbell from opposite chest straight up in line with elbow).