Dropdownlist in mvc 4 using Enum

Thanks

Through this link "http://www.codeproject.com/Articles/662968/Creating-a-DropDownList-for-Enums-in-ASP-NET-MVC" i got some idea. and i used "approach 2" in my code.

but i am new in mvc so how i am use extension method. it is write in model or either in controller. and in view "ToSelectList()" give error.