Questions About Cdl License?

my husband is interested in getting a cdl license. the only license that doesnt require teh road test right away is the “C” license. can anyone tell me what type of truck a class “C” license is allowed to drive? i saw there are alot of endorsements you need to add to the A and B licenses and my husband is not experienced yet, so he wants to just begin with the basic to get experience and practice using a cdl permit then pass for the cdl license ,then add endorsements for the use of bigger trucks ect. where to begin, what is the best and easiest option for beginners ? and what is a class “M” license for?