A lot of people think of any model that has an engine as "Gas Powered" which pay not be what it really is. If you are reading the words "nitro gas" on a web site, it is probably a site like raidentech or nitromodels. The people who run those particular sites are translating product descriptions from Chinese to English and the wording sometimes gets messed up.

The glow fuel (often called "Nitro") that many model engines use is mostly alcohol, with oil and nitromethane added.

As others have mentioned, there are no pre-built gasoline powered models on the market that are for beginner pilots.

Finding a local hobby shop might be helpful so you can actually see the stuff and talk to someone in person. If you decide on mail order, the following are three of the major US distributors and are well known for good customer service:
www.towerhobbies.com
www.horizonhobby.com
www.hobbypeople.net