A rudder turn is performed using the rudder to yaw the nose of the airplane in the direction that you want to turn, and while space does not permit going into all the details, most airplanes will also inherently bank in the direction that the rudder is applied.
There are basically two different techniques required to turn an airplane without ailerons using the rudder. Planes that exhibit a lot of upright stability, such as a high wing powered glider, typically resist banking and therefore requires you to continue holding in rudder to keep turning. These aircraft typically require a larger rudder input to get the turn started, but once started, the rudder has to be reduced to keep the turn from becoming too tight. Note: The inherent skid and subsequent speed loss when applying rudder will most likely require you to combine some up elevator with the rudder at the start of the turn to keep it from dropping.
KEEP IN MIND THAT RUDDER BANKS ARE LESS PRECISE THAN AILERON BANKS AND WILL TEND TO LAG BEHIND YOUR INPUTS IF APPLIED TOO QUICKLY
Other rudder planes require a technique similar to an aileron turn, where the rudder is applied only long enough to bank the wings, and then it is neutralized to avoid over-banking and entering a downward spiral. Similar to an aileron turn, the degree of bank and the size of the turn are dictated by the size of the rudder control input. Keep in mind that rudder banks are less precise than aileron banks and will tend to lag behind your inputs if applied too quickly. Thus, to achieve results that more closely match your intentions, you must apply all your rudder inputs very smoothly to give the plane a chance to keep up with your inputs.
Once the turn is started, you’ll need to adjust the elevator to keep the turn level, then level the wings with opposite rudder to exit the turn. Returning the wings to level usually takes longer with rudder than it does with aileron, thus you’ll have to start leveling the wings prior to the point that you want the turn to stop, and then continue holding in the rudder until the wings are level. Note that prolonged rudder defections and the resulting skids tend to scrub off airspeed, thus you will most likely need to hold in a little up-elevator while leveling the wings to keep the plane from dropping.