Imp Tcodes n Tables in HR module

Hi

Earlier i have worked with SD,MM, and FI modules but right now im into a project which involves HR module.As im new to HR module n wants to know what r all the imp transactions and tables in HR module.

Also my first obejct is involved with creation of PERNR which uses tcode PA40 ,can you please let me know the steps to cre8 PA40 transaction.

Thanks

KV