Draw Straight line on picutrebox?

[Ben3eeE]

Im having trouble making a Paint.exe straight line draw.

You know the one where you point out where to start then hold down the
mouse button and release it to finish the drawing. My problem is that
if i move the mouse back the line should move back with it and if i
spin the mouse the line should spin and dont draw anything before i release
the button.
im using Microsoft visual stuido.net 2003


Heres my code now:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
ritfält.Image = New Bitmap(ritfält.Width, ritfält.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb)
Grafik = Graphics.FromImage(ritfält.Image)
Grafik.Clear(Color.White)
End Sub

'mouse move in the picturebox
Private Sub ritfält_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles ritfält.MouseMove
If drawing = True Then
If Not e.Button = MouseButtons.Left Then Exit Sub Else
Grafik = ritfält.CreateGraphics
Färg = Color.FromName(CStr(PennFärg))
Penna = New Pen(Färg, 2)
Grafik.DrawLine(Penna, sngx, sngy, e.X, e.Y)
sngx = e.X
sngy = e.Y
'force a redraw
Me.ritfält.Refresh()
End If
End Sub

'mouse down in the picturebox
dragging = true
sngx = e.X
sngy = e.Y

'mouseup in the picturebox
dragging = false