Hi!
Sorry, this may not be very helpful, but I will try to remember how to do it. I am assuming you have already saved the pgn file somewhere where you can open it from Fritz. If you have, then you would open the game/file from Fritz. I think you go to WINDOW, LOAD, and you would locate the game. If this does not work, you can go directly to file, right click it and OPEN WITH program - Fritz. [I apologize if I am being too detailed.]
One you have the game up and running in Fritz, you can go to (whatever) analysis level you want. The version I am looking at has "INFINITE ANALYSIS" - (a magnifying glass focused on a 'tablet'.)
I haven't done much Chess in the past year or so I have forgotten a bit of the things I never used to use much.
I hope that helps.
If it doesn't work, check with SonofPearl - I think he has Fritz as well.
Take care.
I'm not sure if my question belongs in this forum. But, I'll try anyway. Can anyone tell me how to analyze a Chess.com game with Fritz? I have analyzed a game I played against Fritz with the program, but not one I have downloaded the PGN for. Thanks!