One way to learn HP-UX commands is to use the key shell (keysh). If you have a terminal that supports function keys, such as Reflection for HP, key shell will turn those function keys into prompts for different commands. Once a command is finished, you'll see the exact command that is submitted to the shell, which makes learning the options easy.
Another good way to get familiar with HP systems is to use the HP-UX Software Recovery Handbook. You can find individual PDF chapters for the handbook on HP's ITRC (I.T. Resource Center): http://itrc.hp.com (login required). Look under the "knowledge trees" for "HP-UX Software Recovery Handbook"