I'm actually glad to hear from young drivers with a hesitancy to drive on the highway. The biggest problems I've seen on the highway have come from the under 25 crowd driving too fast and/or recklessly or the elderly crowd driving too slowly.
However, highway driving
is something that you'll end up needing to do sometime in your life, and being afraid or overcautious can create just as many problems as being reckless.
Practice is the best solution. Stay in the right lane until you have a feel for highway speed and the behavior of other drivers. This way, if you
do get too nervous, you can exit at any exit along the highway (save for the rare left exits) and pull into a gas station until you have time to breathe and readjust.
Once you feel relatively confident in the right lane, learn how to drive in the center lane. Staying in the center lane means that you can maneuver as you need to for exits - right or left - and you should be looking far enough ahead that you'll also be able to maneuver as necessary for road construction or other obstructions in the right or left lanes without too much difficulty. It's sometimes intimidating to ride in the center lane because traffic tends to cut in and out in front of and behind you, but you'll come to realize that while they're making risky maneuvers to cross three or more lanes of traffic for an exit, you only have to move once.
Just don't follow the average highway driver's example and end up using various hand gestures at other drivers. That never solves any problems.