Well, you target a person by pressing primary fire (left-click by deafult) while the crosshair is on them. Once they are targeted, you can press left click to start a "swoop", which will rapidly close the distance between you and your target. As you approach your target, use Right Click to hit him/her. If you are trying to attack an enemy that is targeted, then you may HOLD right click as you approach and still be able to hit him/her. If you are trying to hit a person NOT targeted, you will have to click the right mouse button at the right time to hit them. For more help, look at the Melee Tutorial at the top of this section. =]