Still exporting text, and a further question

Hi:  I've been plugging away at exporting text from VB 2010.  Moving right along, but now Im at the stage where I want to deliver a prompt to users to allow them to select or enter a filename.  In short, I'm including a savefiledialog code with streamwriter code; I don't know where to insert the savefiledialog code.  Below is what I have so far:

Dim objFile As New System.IO.StreamWriter(SaveFileDialog1, True)

        SaveFileDialog1.Title = "Specify Desitination Filename"
        SaveFileDialog1.Filter = "Text Files (*.txt)|*.txt"
        SaveFileDialog1.FilterIndex = 1

        objFile.WriteLine(RichTextBox1.Text)
        objFile.Close()

Thanks in advance.  Robert