Changing the starter on a 1991 Chevrolet truck should not take very long. The starter is easy to access from under the truck and the bolts are easy to unscrew with a socket wrench.
To ensure the starter is bad, take it to the automotive-parts store to have it bench tested to ensure it is indeed faulty. The parts store will be able to tell if it is bad before you buy a replacement.
Prop open the hood for access to the engine compartment. Disconnect the battery by unbolting the cables at the top of the battery.