how to set the assignement group of the operator in a field when he logs an incident???

 

hi all ,

 

i am newbie  to sm below is my requriement in IM

 

need to Create a new field Requestor assignment Group. If the Requestor is part of any assignement group then Capture the Assignement group name in "Requestor Assignement group field"

 

in short

how  to set the assignement group of  the operator in a field when he logs an incident???