redirect to a sub domain

i want to permanently redirect (301) from a

www.miosito.com/games

to

games.miosito.com

How I can do this ? (I understand that I have to use the apposite module of sef advance
but I have to know what exaclty I have to write down in the form for correctly redirect)

In Redirect field:
games/ => games.miosito.com

Thanks a lot