Firing inputs to an entity via lua

Say I have a door, and want it to open after some time from the start of the game. How do I do it?

You have to get the entity of the door. You need some way to recognize it or save the entity in a table, but that’s your job. Then just use door:Fire(“Open”,"",0) when you want (or set the number to the delay you need).

Refer to http://developer.valvesoftware.com/wiki/Func_door if you have questions on the inputs/keyvalues of a door.