Add items to a listbox

Try

                Dim di As New DirectoryInfo(Application.StartupPath & "\Characters\")
                ' Get a reference to each file in that directory.
                Dim fiArr As FileInfo() = di.GetFiles()
                ' Display the names of the files.
                Dim fri As FileInfo
                For Each fri In fiArr
                    If fri.Extension = ".png" Then
                        TotalCharactersFound += 1
                        Dim s As String
                        s = fri.Name
                        ListBox1.Items.Add(s.Substring(0, s.Length - 4))
                    End If
                Next fri
                Label1.Text = "Total Characters Found: " & TotalCharactersFound
            Catch ex As Exception
                MsgBox(ex.Message)
            End Try