Simple vehicle Respawn

[SaBrE]

I searched for ages on this but never found a clear-cut answer. I'm new to MP scripting so it was all gibberish to me. I want a simple trigger that will spawn a vehicle (just one, not one for each player) after 5 minutes or play in a certain position (on top of a H Invisible), with a message everyone can see that says "Vehicle has spawned". Can people tell me what to do right from the start, including the use of gamelogics, createvehicle commands... the lot.

Thanks very much,

Sabre

EDIT:
Did it. It should have worked the first time but I stupidly put this instead of true on the triggers. I did it a cheating way; I setpos the vehicles that are already on the map to an invisible H. Works fine and both PCs can handle it.