when want to check windows update setting then in dailog box "written that windows update cannot currently check updates,because updates on this computer are controlled by your system administrator". then here who is my windows administrator.and how i can change my windows update setting?? 

Hi,

If you are using configuration manager for Windows Updates then that is the message you will see in the Windows Update tab on the clients as administrator(SCCM) has defined a WSUS server instead of using Microsoft Update.

So you control the updates using Configuration Manager Software Updates groups and their schedule and restart settings in Client Settings.

Regards,
Jrgen