How do i create a game like Subway Surf (Infinite terrain)?

You are better off asking this question in the Forums : http://forum.unity3d.com/

Sorry, but your question is too broad, and this is not the place to ask for scripts. Unity Answers and its community is here to help you solve any Unity-related problems you have, not give away free code. If you don't know how to write code, I suggest learning Unity's Java Script (its really easy), but if you don't have time, or whatever, then you can try asking your question on the Unity Forums. I hope you can get an answer!

Also, use google. Do tutorials, and learn how to use Unity.

Here is a list of tutorials to get you going :

Start at the bottom and work up : http://www.unity3dstudent.com/category/modules/essential-skills/

Start at the bottom and work up : http://www.unity3dstudent.com/category/modules/beginner/

the Unity Wiki : http://wiki.unity3d.com/index.php/Tutorials

A list of resources : http://answers.unity3d.com/questions/12321/how-can-i-start-learning-unity-fast-list-of-tutori.html