Get the IBM DOS user manuel or something similar... perhaps in some old second hand book store for the price of the paper or less... those books contain a lot of usefull info.
If I have the time I will take a look on old harddrives for some txt versions... other possiblity search the net.
If you have a win98 disk the old Dos commands are on the cd.....its inbedded in some dir. do a search for old msdos on the cd. There is a file called "help"(what else) It gives detail on all the old commands....just type :help: in that dir. You can then try some of them out to get the hand of it