My antenna in a similar TT is a fixed, non-steerable omnidirectional antenna (receives equally poorly in all directions). To troubleshoot, and not to assume your friend doesn't know all this:
Trace the cable from the back of the TV to where it connects into the wall. It should go to a connector labeled "TV" or "Antenna," and not satellite. Mine also has a short jumper cable that allow the user to select another source to route to the antenna connector. The pathway should make sense, from antenna to TV.
Turn on the TV, press the Menu button on the remote to select "Input" or "Source" to "Antenna." There may be a dedicated button that does this.
From the Menu, there should be a "Scan for channels" option. When I first used my RV's TV, the last time I had used an antenna was way back in the analog days when we had discreet channels to select. If one has not used over-the-air digital TV, this may not be obvious. As Wiscampin said, you have to scan for (digital, antenna) channels every time you move to a new location to find what is there. The channel scan may take 10-20 minutes. When it's done, you will probably get an on-screen message telling how many digital signals were found.
BUT, if one is in an area distant from TV stations, that &@$#% omni antenna may not find a single channel. That has happened to me.
Coachmen Freedom Express 192RBS