I am 15 my parents have a 40 acres of field i can fly in. I was wondering our property is always busy with planes and helis flying overhead. Do they cause interference to the transmitter or recevier?

You won't get interference from them. They are on a different frequency. Just don't go so high that you interfere with them. If you have that much traffic over your property, are you close to an airport? There are special rules about flying near an airport. If you're near an airport, ask your instructor if you'll be breaking any FAA or AMA rules by flying there. He should be able to tell if you'll be breaking any laws. - Joe

I am teaching myself and don't have an instructor. i am about 20 miles from the nearest airport

Read some of the other posts here about people trying to teach themselves. You might want to reconsider.
Dennis-

You are not breaking any laws as long as you give them the right of way,luck,let us know the results,they're radios are on different fre.

Thanks alot