After updating to new version of CP3 Service, site MAY no longer be configured in IIS.  If it is and bindings are correct and you can check the service status page and it shows the correct version, you are done. 
https://cp3-service.[domainname]]/api/service/status

If it is NOT configured in IIS anymore, then do the following:
Open Powershell ISE and enter the following:
Set-ExecutionPolicy RemoteSigned
And run it
Make sure create-site-and-app-pool.ps1 and logger.ps1 scripts are in same folder.
Note if you downloaded the scripts from internet, right click them and choose Properties, then pick Unblock at bottom before running scripts.
Then run the create-site-and-app-pool.ps1 script.  Check to make sure site is created in IIS and bindings are correct after running.