Hey buddy there are many ways around this, but the easiest way that I would suggest since your using the "Lasso" tool to draw, would be to just draw your circle, then go up to Edit/Stroke, then choose how thick you want the stroke, then choose white in the box directly below where you set the thickness of the stroke. Then just hit Ok.
Cool drawing! (Great movies)
Select the layer you're drawing on and change the blending mode back to "Normal".
Currently your layer is set to Multiply so you are unable to see white pixels.
Hope you find this helpful!
Thank you for your help. i changed the line work layer to normal, but i also moved the line work layer to the top so that the white shows through and it works!!. thank you for your help!!