That depends on the format of the file containing the game. What is
the name of the file you're trying to use?
*.d64 or *.g64:
File Attach disk image, then type LOAD "$",8 + ENTER, then LIST + ENTER,
then LOAD "filename",8 + ENTER and finally RUN + ENTER.
*.t64 or *.tap:
File Attach tape image, then type LOAD + ENTER, then RUN + ENTER.
Or you could just try File Smart-attach disk/tape.
"If anyone disagrees with anything I say, I am quite prepared not only to
retract it, but also to deny under oath that I ever said it." -Tom Lehrer