That's a very simple question, however the answer can be simple or very technical.

Simply stated, to turn (called a bank) you tilt the wings.

Depending on the design of the plane, that is accomplished by moving the ailerons. These are the pair of movable control surfaces attached to the trailing edge of each wing tip. (see the attached picture) They move in opposite directions so when one moves down it forces that wing up, and at the same time the other aileron performs the opposite action. So, to bank the plane to the right you would have the left aileron move down and the right aileron move up.

As I noted, that is the simple explanation but it will give you a place to start.

There are many factors that affect the flight of an airplane - RC and full scale. Since you stated you don't know the technical terms it may be in your best interest to gain some basic understanding from a book or website. One of the best books I have found is called "Stick and Rudder" by Wolfgang Langewiesche. Subtitled "An Explanation of the Art of Flying". You can do a search for it and find it for $15 or less.

There are many websites that will teach you some basics too, but as you will discover, a lot of information will be provided by the folks right here at RCU.