Powershell to add text to an active directory field for set of users

Question

Could someone help or point me in the right direction to do the following in PS please?

I need to put populate a field in AD with some txt which will be the same text for a group of users, it needs to add the text to all members of a particular group/

Thanks

Answer 1

..........

Answer 2

I thought I had this worked out, these two commands work when there is one member of the group (when I was testing), but as soon as I add >1 it fails to run.

$Names = Get-AdGroupMember -identity "Staff"

Set-ADUser $Names -MobilePhone "Testing"

Can anyone help with what I have done wrong please?