Hi Samid
ST03 - Workload monitor, you can find the over all post action information's, kindly refer the below link
http://help.sap.com/saphelp_47x200/helpdata/EN/2d/b8be3befaefc75e10000000a114084/frameset.htm
Transaction codes SM66, AL08 & SM04 used online information about the user activity's
Sm66---->Global Work Process Overview
Monitor the work process load on all active instances across the system
AL08---->List Of All User Logged On
Shows the list of all the users which are logged on to the system globally or for all the instances in the system which are active.
SM04--->User List
Shows the list of the users which are logged on to the instance in which you are currently logged in. Can say for the local instance.
Regards
Ram