You should ask in a Gaming group.  But I suspect you either click Start,
Run, type the command into that pane, or take the shortcut to the
executable for the game, and add the command just beyond the Target
line, like this-

Original file path:

"C:\Program Files\Kill and Maim"

File path with parameter:

"C:\Program Files\Kill and Maim" cheat#1

or

"C:\Program Files\Kill and Maim" /cheat#1

In any case, the space between the path and the parameter is necessary.

hth,

Use Google to search on the name of your game (which you chose not to
identify here) and on cheats for it, like "+<gamename> +cheats".  You
could also go to the game maker's web site to see if they have forums
where you can ask about cheats for your unidentified game.

Rarely do games use command-line parameters to enable and define cheats.
Usually they are enabled and defined in a configuration file.