How to edit only the Firstname (givenName) of multiple users and import with csv

Hello Powershell Masters!! I hope all is well this morning :)

I was hoping the community would be able to help me. I looked all night at different scripts, but I was unable to find one for my specific need. If I have a list of users where the samAccountName for all the users are all numerical Example, 745744, 745746, etc…. I was looking for a powershell script that could accomplish the following:

1. Put an “XX” without quotes in front of the users first name or givenname
2. Have the script import the list of users from an csv file if I have a list of all the users samAccountName
3. I don’t know how I would format the csv file…. Do I need only one column that says samAccountName?? How would we format the csv file?

Thanks everyone in advance. You guys/gals are awesome!