New C# class in ASP.net - I can't use it!

[arashkk]

I have defined a new class in an ASP.net project. When I compile the website I recieve this error "The type or namespace "Class1" could not be found (are you missing a directive or assembly refrence?)"
I even moved the class file to the website folder and then to the Add_data folder and each time removed and added the class in the project. But yet I receive this error message. Would you please help me? Once I put the class in a namespace and wrote "using NameSpaceName" in another file, but also it didn't help. What does mean "assembly refrence here?" will it solve the problem?

[tlhintoq]

Bytes has a policy regarding assisting students with their homework.

The short version is that the volunteers here can't help you with schoolwork.
A) We don't know what material you have and have not learned in class.
B) We don't know the guidelines you must follow.
C) In the long run giving you the answers actually short changes your education.