aaw.. hope your son gets well soon.
"ALT-tabbing" = Hold ALT key left side and press TAB (above caps-lock) then release when desired prog is chosen or to go to desktop.
you can also of course go on Teamspeak before you start the game if that is easier.
In the new members section there is a list of ways to find NRU on xfire, steam etc.
xfire, teamspeak are preferred.