How to automatically run add-in when workbook opens

I have this Add-In code below that works for me fine when I run it under macro's but how can I get this to run every time this excel file is open? this will be a shared file and most people don't even know how to get to macro's to run them let alone what they are. So I would like to have this Menu Command run when a user opens it so it will always be there. I have copied this from a place before and it works but I just can't get it to run automatically when the workbook opens.

Sub DeleteMenu()
    On Error Resume Next
    CommandBars(1).Controls("Add Employee or Product Code").Delete
End Sub
Sub CreateMenu()

Dim HelpMenu As CommandBarControl
Dim NewMenu As CommandBarPopup
Dim MenuItem As CommandBarControl
    'delete the menu if it already exists
    Call DeleteMenu

    'find the Help Menu
    Set HelpMenu = CommandBars(1).FindControl(ID:=30010)

    If HelpMenu Is Nothing Then
        'add menu to the end
        Set NewMenu = CommandBars(1).Controls _
                      .Add(Type:=msoControlPopup, temporary:=True)
    Else
        'add the menu before help
        Set NewMenu = CommandBars(1).Controls _
                      .Add(Type:=msoControlPopup, before:=HelpMenu.Index, _
                           temporary:=True)
    End If

    'Add Caption
    NewMenu.Caption = "&Add Employee or Product Code"

    'First Menu item
    Set MenuItem = NewMenu.Controls.Add _
                   (Type:=msoControlButton)
    With MenuItem
        .Caption = "&Add New Product Code"
        .FaceId = 162
        .OnAction = "AddNewProductCode"
    End With

    'Second Menu item
    Set MenuItem = NewMenu.Controls.Add _
                   (Type:=msoControlButton)
    With MenuItem
        .Caption = "Add Employee"
        .FaceId = 162
        .OnAction = "AddEmployee"
    End With

    'Third Menu item
    Set MenuItem = NewMenu.Controls.Add _
                   (Type:=msoControlButton)
    With MenuItem
        .Caption = "Don't click me!"
        .FaceId = 536
        .OnAction = "checknames"
    End With



End Sub

Function CommandBarExists(n)
Dim cb As CommandBar
    For Each cb In CommandBars
        If UCase(cb.name) = UCase(n) Then
            CommandBarExists = True
            Exit Function
        End If
    Next cb
    CommandBarExists = False

End Function