Create and Use Classes

Hi, please help me,
Please correct me if i'm wrong on my process of creating and please teach me how to use a Class
1. In Visual Studio, i right click on my Project then select "Add New Item"
2. Then i select the Class Icon
3. It created an App_Code Folder and the Class File "Class1.vb" is placed there
4. I open the Class and enter some code like this.
Imports Microsoft.VisualBasic Imports System.Web.HttpResponse Public Class Class1 Public Sub Check(ByVal x As String) If x = "" Then 'This condition will check if the passed "x" string has value if not 'it should go to another page by redirecting End If End Sub End Class

     Question 1: why does i can't just enter a simple "Response.Redirect("url.aspx") inside the if statement?How?
5. I now go to the Co ...