Trying to call a function from another file

I have a function in a class file called auth_user and its in App_code folder. I am trying to call that function from random pages that are on the website. Inside the class f开发者_Python百科ile is a function that is simple, basicly check for flags in the sessions, i just wanna have it there so i dont have to type it again and again. I want to be able to call it with one function like auth_user();

How would i do this excetly ? would the function be public static void or what ?

Static makes sense for this:

public class AuthUtility
{
    public static bool IsUserAuthorized()
    {
      ....
      return retVal;
    }
{

And then you would call it:

AuthUtility.IsUserAuthorized();

Edit Based on Comments

So, not to be rude, but that information in your comments would've been pertinent in your original question and saved a fair amount of time.

Regardless, you'll need to pass in either the current HTTPContext or the Current Session into your static method:

public class AuthUtility
{
    public static void AuthorizeUser(HttpSessionState currentSession)
    {
        currentSession["whatev"] = "rockin";
        .....
    }
}

And the you would call it:

AuthUtility.AuthorizeUser(this.Session);