[HELP} Asynchronous loading assets after loading scene

Suppose i have Terrain and first person controller with some game object. After deploy as a web executable the size is 4mb. Without the game object ( only terrain,first person controller and some trees) the size is 2mb. So its easy to download when somone goto my site. But 4mb takes too much time to download. Is there any way that after loading my scene with only first per. cont. terrain, and some trees, the other game object will load asynchronously??? Means i want to load .fbx file from my webserver after loading my scene and place it to right postion which i placed it in my terrain before when i was developing its. I got some hints like assets bundles and downloaded the example project but i cant understand. Can ny one hlp me with this with some sort example? Thanks in advanced.