I am very new to vb.net. I just starting taking it at school and I am having a hard time with it. Here is an order project we need to do for class. I can't get rid of the comma between the names in the list box and my decimals don't seem to line up either. I am very frustrated with this any help would be appreciated. Thanks.

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Customer, Last, First, Address, City, Chairs, Sofas, Invoicenumber As String
        Dim CommaName As Integer
        Dim Datum As IO.StreamReader = IO.File.OpenText("C:\Temp\assign2.txt")
        Dim Chair, Sofa, Tax, Cost, SalesTax, Total As Double
        Chair = CDbl(Datum.ReadLine) * txtchairs.Text
        Sofa = CDbl(Datum.ReadLine) * txtsofas.Text
        Tax = CDbl(Datum.ReadLine)
        Cost = Chair + Sofa
        SalesTax = (Chair + Sofa) * Tax
        Total = Chair + Sofa + SalesTax

        Customer = txtcustomer.Text
        CommaName = Customer.IndexOf(",")
        Last = Customer.Substring(0, CommaName)
        First = Customer.Substring(Customer.Length - CommaName + 1)
        Address = txtaddress.Text
        City = txtcity.Text
        Chairs = txtchairs.Text
        Sofas = txtsofas.Text
        Invoicenumber = (Customer.Substring(0, 2).ToUpper & City.Substring(City.Length - 4).ToUpper)
        With ListBox.Items
            .Clear()
            .Add("Invoice Number: " & vbTab & Invoicenumber)
            .Add("")
            .Add("Name: " & vbTab & First & " " & Last)
            .Add("Address: " & vbTab & txtaddress.Text)
            .Add("City: " & vbTab & txtcity.Text)
            .Add("")
            .Add("Number of Chairs: " & vbTab & txtchairs.Text)
            .Add("Number of Sofas:   " & vbTab & txtsofas.Text)
            .Add("")
            .Add("        Cost: " & FormatCurrency(Cost))
            .Add(" Sales Tax: " & FormatCurrency(SalesTax))
            .Add("" & vbTab & "" & "----------------")
            .Add("Total Cost: " & FormatCurrency(Total))
        End With

    End Sub


    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        ' Clear all display in text list box
        txtcustomer.Text = ""
        txtaddress.Text = ""
        txtcity.Text = ""
        txtchairs.Text = ""
        txtsofas.Text = ""
        ListBox.Items.Clear()
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        Me.Close()
    End Sub

    Private Sub ListBox_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox.SelectedIndexChanged

    End Sub
End Class

A couple of changes to your code.
1. A better name for CommaName is CommaPosition - more discriptive
2. When you get the first name use instead:

First = Trim(Customer.Substring(CommaPosition + 1))

If you don't give it a length it will take everything to the end of the text and the trim will get rid of any spaces.
Hope this helps.