Last I saw most of the trucks used for training are old company trucks. That would mean that they are 10 speeds.
The pattern looks like this
R - 7/2 - 9/4
1/6 - 3/8 - 5/10
You will not use 1st much, it is very low. Mostly you will be starting in second when loaded, and maybe 3rd when empty.
The hard part for me with a 10 speed was getting use to 6th hiding down in that corner. Especially with down shifting.
Another common tranny is the 9 speed, but I doubt they will have any of those at the school. It is almost the same as the 10 speed, but 6th is not down in the lower left corner, it is up where 7th is on the 10 speed. So it is a more conventional H pattern.
You should not have any trouble learning to shift a truck. Since it is not the same as shifting a car, you should be able to pick it up well faster than someone that has driven a car with a manual.