There is a servo to operate the engine. The servo plugs into the receiver (rx) and the engine gets connected to the servo via push rod.

Great Planes has very good instructions with their ARFs. Read through it once or twice before you start assembling the plane. You will have a much better understanding of what's going on. They will also list the building materials you need right in the beginning (types of glue, etc.).

Do you have a radio? It comes with the receiver, and battery and charger for the plane.

I'm sure others will chime in on lots of good tips and recommendations.

Welcome, and Good Luck!