You have 3 servos the operate the swash. The work through swash mixing in the radio. For your Trex 600 you will have a 120 deg swash. That means ch2 will be aileron , ch6 will be pitch, and ch3 will be elevator.
When you push the left stick up. The radio mix will move all three servos up (giving you positive pitch).At the same time it will add throttle increasing headspeed. When you move the right stick forward it will raise the elevator servo tilting the back of the swash up (this causes the heli to move forward). When you move the right stick to the right the aileron servo will move down and the Pitch servo will move up, titling the swash right. This will roll the heli to the right.