The best way to do this is to learn/practice by somebody with an experience and in a relevant institution.
A good option will be to have dump truck training in one of the construction companies near you! They mostly use a heavy machinery at the construction sides, so having trained with various machines including dump truck training, will be ideal for you.
So, I don’t want to bit the dead horse, but let me repeat it one more time! If you want to be a dump truck driver, you will have to have a valid driver’s license that’s renewed on a regular basis.
Moreover, you will need to have a valid CDL license or a learner’s permit for a CDL in the future.
If you want to drive a straight dump truck, you will need a Class B CDL. With that one, you can drive heavy other straight flatbed and box trucks as well. In other words, you can tow trailers less than 10,000 pounds of Gross Vehicle Weight Rating (GVWR).
Certain trucks, that are considered tractor-trailer dump trucks, require a Class A CDL. With that license, you can tow trailers that are more than 10,000 lbs. GVWR.