Many people think that the mechanics of driving a truck are very difficult, but, if you know how to drive a manual transmission, you are already half way there. Most trucks have a manual transmission that is set up like a five-speed car. Five forward gears, one reverse gear, setup in an “H” pattern. The different with commercial trucks is that gears 1-5 are considered “Lo”, and gears 6-10 are considered “High”. So, to get to the higher gears, you have to flip a switch on your shifter, to “High”, and you will be able to shift into the higher gears. With trucks that have more than ten gears, the shift pattern is the same, but there is just more switching on the gearshift, from lo, to high, and up.
Also like a manual-transmission car, it is required that the clutch be pushed all the way in when starting from a complete stop, but, when you are shifting gears, it is only required for the clutch to be pushed in far enough to break torque, not necessarily all the way to the ground.
So don't let your fears of driving a semi get in the way of starting a truck driving career!