Zandona,

First, it appears you want to know how to do a roll with a 3-channel airplane. Planes that steer with rudder are generally high wing with dihedral. Both the wing location on top of the fuselage and dihedral will cause roll in the direction of the rudder when it is applied. We call this "roll due to yaw."

Visualize your plane flying through the air. You put in and hold right rudder. This causes the plane to yaw so the airflow hits the left side of the fuselage. The airflow splits to go around the fuselage. The air going around the top of the fuselage hits the underside of the wing causing a roll to the right.

Next, visualize a wing with a lot of dihedral. Yaw it to the right. The air flow now hits the top of the right panel and the bottom of the left panel, both causing roll to the right.

The combination of these 2 will give a pretty good roll in many planes.

Second, you mention a "barrel roll." A barrel roll is a specific maneuver that is a spiral rather than an axial, or aileron, roll. Rudder only planes tend to do barrel rolls naturally rather than axial rolls, which aileron planes do very well. Doing a barrel roll with an aileron plane requires you to hold a slight amount of elevator during the maneuver to get the spiral rather than a roll around the longitudinal axis of the plane.

To do a roll with a rudder plane. Go to full power. Raise the nose 15-20 degrees and release all the up elevator. Put in full roll control and hold until the roll is complete. Recover from the slight dive. This roll is best done "by-the-numbers," step by step without any mixing of the controls. Raise the nose, release, roll, release, up to recover, release.