If you're trying to say "Maria is sleeping.", then it is correct.
Usted, I believe if that is what you are asking
The answer will be "salir" this will make the sentence look like Recuerde salir del sistema despues de usar una computadora. this means remember to get out (or log off) of the sistem after you have used the public computer.. entrar mean enter utilix
Hope this helps
Can u said it on English?