By gas I assume you mean a regular glow fuel powered Trainer. There are many to choose from. Sounds like what you want is an ARF by what you said. They will be pretty complete in that they will have the fuel tank & most or all necessary hardware, leaving only the engine & radio equipment needed. Remotes are what we change the channel on our TVs with. You apparently have a decent Transmitter so you will need a reciever (with matching channel chrystal) for your Transmitter & 4 servos. This can usually be bought as a flite pack. We need to know what brand of Radio Transmitter you have to steer you in the right path flite pack wise so there are no compatability issues. Here is Tower Hobbies page of Trainers in the most popular size range.

http://www.towerhobbies.com/listings/cat-cat-a.html

Here is the link to the engines that will power them. The OS .46 AX being the engine of choice for most people if you have the money, if not some of the less expensive engines will still suffice just fine for a Trainer.

http://www.towerhobbies.com/listings/cat-cat-g.html

If you tell us exactly what you have in the way of radio equipment, we will be able to tell you what you need to go with it.

As stated above by Missleman, you'll want to seek out the local club & inquire about joining, Insruction, & you will also need AMA membership as well.
Good luck!

I was trying to put up the pages that show the whole list of what they have to offer but apparently doing it that way only gets you to the category page.

click on the link that says: RC Aircraft Trainers Allmost-Ready-To-Fly .20-.50


then for the engines click the link that says: RC Engines- Glow Fuel Aircraft-2 stroke- .20-.51