Most of the time it's not necessary to have exercise equipment in order to exercise. You can generally use your own body weight as a counterbalancing weight, but if you're interested in building massive muscle, then you do need to either hit the gym or purchase some equipment to achieve optimum bulk.
Check out this fitness tutorial to learn how to do the standing preacher bench to tone triceps and biceps. The bench will help you stabilize your triceps as you pull upward with your forearms.
Work very hard on linking up your "mind muscle" connection.