How to get one acting gig?

Go where there's some local news being filmed and get in front of a camera - maybe offer an opinion or something.

Otherwise you can try for being an extra. No experience is required, but you do need to live near where they are filming things. You can register with a casting company in your area (like Central Casting). Or you can register on a website like http://www.extrasaccess.com or backstage.com to find calls for extras and submit for something that way.

The easiest? Be an extra by traveling to a place where they're filming crowd scenes. (My husband is in The Towering Inferno--but we only know it's him because he remembers exactly where he was standing.) Another is to be part of the audience in an infomercial.

You couldn't get a real acting role without years of training and experience.
You could get a job as an extra, or you could try for a place on a game-show.
But if your goal is a real acting role, that's not going to happen.

If you just want 'to be on tv' you can try applying to be on a game show, or, even easier, to be in the audience of a tv show. Or you can try the very sensible suggestions from other posters, and register with an extras agency. Good luck.

Community theaters will often take anyone for an acting job even someone without experience at least around here they are always looking for people to play parts.