admin account

i downloaded a game called mars rover. when i click on it
a message comes up saying setup incomplete, that i must
run it once as administrator account. i tried right
clicking on the game, (RUN AS came up and i choose it)
however i could not get the correct user and password.
can someone let me know whats going on and give me a step
by step to resolve this, you will make my 6 year old
happy!

thanks, pete