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(ByVa l sender As System.Object, ByVal e As System.EventArg s) Handles MyBase.Load
ritfält.Image = New Bitmap(ritfält. Width, ritfält.Height, System.Drawing. Imaging.PixelFo rmat.Format24bp pRgb)
Grafik = Graphics.FromIm age(ritfält.Ima ge)
Grafik.Clear(Co lor.White)
End Sub

'mouse move in the picturebox
Private Sub ritfält_MouseMo ve(ByVal sender As Object, ByVal e As System.Windows. Forms.MouseEven tArgs) Handles ritfält.MouseMo ve
If drawing = True Then
If Not e.Button = MouseButtons.Le ft Then Exit Sub Else
Grafik = ritfält.CreateG raphics
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.Refr esh()
End If
End Sub

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

'mouseup in the picturebox
dragging = false