How to pass data from a class file to a listbox declared in aspx page

Hi I am new to programming and I am trying to pass the result of sub procedure located in a class file to a vb file, but I am getting listbox not declared error in my class file. I would greatly appreciate any help. Below is my code.
Class File
Imports Microsoft.VisualBasic
Namespace EvrensCode
    Public Class reusablestuff
        Public Shared Sub calculatedensity(state As String, pop As Double, landarea As Double)
            Dim density As Double
            density = pop / landarea
            ListBox1.Items.Add("The density of " & state & " is")             ListBox1.Items.Add(density.ToString("N1") & ...