Hi guys.i’m noob on unity, beginner. i have a problem with environments in asset store. i downloaded 3 of them. but if i put my character on the stage. he will fall though. any fix ideas? i heard that before unity 5 version there is a option called. object to terrain. i think its the important thing. but i can’t find it in unity 5. HELP ME PLS 
Make sure that everything has colliders attached to it. You also need to put your character a bit above the ground. Otherwise he will still fall through.