Changelevel to mp_coop_lobby_2
How I can change level to the mine?
Maybe here?
http://img200.imageshack.us/img200/6927/79763783.png
http://img848.imageshack.us/img848/3228/84997885.png
$LevelCompleteRelay would be a custom relay you will make to change the level of your map (i.e. a relay that points to a point_servercommand that has inputs: "OnTrigger point_servercommand command "changelevel mp_coop_lobby_2"). It could also be used to execute other commands once the loading movie has appeared. Though I don't see anything else you can execute at the loading screen.
$trigger_this_to_change_level I think does nothing as I could not find this parameter in any entity within the coop end level instances. This could have been Valve's intention to create an easy way to change levels.
$DoorNameOutsideHallway in the example coop map 'doors' is transition_door_1. However there is no entity (in the instances or in the level) named that. I would ignore this value until we know more about it.
$DoorNameInsideHallway This would be your door that is before your exit (otherwise known as @exit_door).
Remember to use a point_servercommand, not a point_clientcommand to change the map level. Sometimes it takes a little while for it to trigger the relay, making the robots wait in the disassembles before the cut-scene. This is probably a script that has been executed by the spawning instance. I'm not entirely sure but I could make a custom instance to remove the wait.