You have multiple problems.
You've got the script name in there twice along with ":File" which doesn't belong, and you have "dot space backslash" which won't work. To dot source a script you need to use "dot backslash scriptname". But that won't work either because your current directory is C:\Users\Me and the script appears to be in the PS_Scripts subfolder.
cd \ # root of c:
C:\Users\me\PS_Scripts\Graph_SPO_shared_files1.ps1 -Sites "https://MYTENANT.sharepoint.com/sites/DevelopmentTestSite"
cd C:\Users\me\PS_Scripts\ # change to scripts directory.
.\Graph_SPO_shared_files1.ps1 -Sites "https://MYTENANT.sharepoint.com/sites/DevelopmentTestSite"
Like this.