How can I load level in the background ?

Basically I have to load a tiny level first (maybe 1 -room level), so that player almost instantly appears in the game world. While player is on the small level, I need for actual level, where whole gameplay is going to happen, to be loaded in the background. So when it’s done loading and spawning all the actors, a menu or a door activates on the small level, allowing player to begin playing game (by either entering opened door and teleporting to the main level; or by selecting “Start Game” in the menu and spawning on the main level).

Is it possible? How do I do that? Thanks.

You need Level streaming: