Importing Multiple Users/SGs from Txt File to FIM portal using powershell

Hi

   I have a list of users in text file. These are users from an app on which IDM is being implemented. As a part of the initial load, i would like to add these users(who are in a text file) directly to the group that will be created in FIM Portal. Can anybody help me do the same using powershell scripts?

Thanks & Regards,

Rajesh K