I am kinda new to rc planes and am looking for a engine that would be good for a beginner.. I have a futaba 4 channel Tx and want something that has throttle control. If someone could explain the different sizes of engines or send me to a web page. I would appreciate it

The engine sizes typically match the plane size. I would suggest you find a local club and look at what they are flying. You may not know how to fly and will need help in learing that and in purchasing your trainer. Regards BobH.