How do you upgrade weapons in zombies

On Kino Der Toten when you turn on the power first NOVA 6 zombies start
appearing but the teleporter and link pad (In the Theater and Lobby respectivly)
will turn on. To link these two have someone run to the lobby and stand on the
link pad. It should say "Hold "X" to link the teleporter." do that and you might
have to do that inside the teleporter. After thy're linked Have everyone get inside
and teleport to the room above the theater or the Pack-a-Punch room. There
you will only have 30 seconds. On FIVE it is a little trickier. to do this go to the
Basement floor and turn on the power. Go back up to the next floor and you
should see that the defcon lights should be all green. Walk up to it a switch and
use "X" to switch it to the next level. once you hit 5 all the teleporters will have a
Pack a Punch hologram and lead to it