No, the USB is not for connecting to the TV. That's for viewing photos from a USB thumb drive. She'll need an HDMI connection, but her Dell Latitude doesn't have an HDMI out. Many laptops will have VGA out, and it's possible that her TV has a VGA input. This would work, but it isn't the best way to connect it because it's analog, not digital. Her laptop does have DisplayPort for video, though. So what she'll need is a DisplayPort to HDMI adapter, and an HDMI cable. Both of these items can be found at Monoprice.com, or at a local store.
After plugging in her laptop to the TV, she'll need to select that HDMI input and adjust her laptop's display resolution to something close to her TV's resolution. An HDTV's resolution will be a lot lower than her computer's, so icons and text from her computer will look quite large on the TV.