Add Existing Users To a Group

I am creating a group named MSProject01. Then create a txt file in the format below.

User

user01

user02

user03

Run the Powershell command

Import-csv "filename.csv" | %{ add-adgroupmember "groupname" -member $_.Users }

You can run the command below to see how many members are there in the group

(Get-ADGroup MSProject01 -Properties *).member.count