Divide an Arc

I'm looking for some tips on how to divide an arc. I am using the "DIVIDE" command, but it doesn't seem like it is doing anything. I also read that after the "DIVIDE" command, you should use the "DDPTYPE" command to get the division points to show. When I use that command I get an "unknown command" error. If anyone knows of a step or command I might be missing, that would help a lot!