Hi Steve,
There isn’t (yet) an option to print photos directly from within Google Photos, so the best option is to download the photo(s) you wish to print first, then print from your computer.
If you are using a mobile device and viewing Google Photos on your phone, tablet/iPad, AND have a printer that talks to your device, then you do have an option to send items to the printer that way.
From memory I don’t think your printer is AirPrint-enbabled though.