1 Create a new 300x300 pixels, black background image ( File > New ).
Add a new Raster layer ( Layers > New Raster Layers )
Pick the Freehand Selection Tool and follow the number sequence as shown in the image.
2 Set your Foreground Color to White and Floodfill your current selection. Deselect your selection by pressing CTRL+D. Apply Gaussian Blur (Adjust>Blur>Gaussian Blur > Radius = 10 )