Open GIMP by double-clicking on its icon. Click on the "File" button and scroll to "New File."
Open the "Image" menu and scroll to "Canvas Size." Enter the desired size in the text-fields and press "OK."
Draw the first image of the animation using the "Brush" and "Pen" tool. Click on the tool within the "Toolbar," and click on the Color Wheel. Mouse-over the wheel until the box displays the desired color. Left-click. Draw by placing the cursor over the canvas and pressing the left-button of the mouse down. Hold the left-button down as you drag the mouse in the desired direction. When you complete the line, release the mouse button.
Highlight the entire canvas, right-click and scroll to "Copy."
Click on the "New Layer" button. Drag this layer so that it rests at the bottom of the "Layers, Channels and Paths" box. Right-click inside this layer and scroll to "Paste."
Open the "Image" menu, scroll to "Colors" and click on "Levels." Click on the arrow in the middle of the slider. Drag the arrow slightly to the left to lighten the image. This begins the process of fading to white. To fade to black, drag the arrow slightly towards the right. Press the button that reads "OK."
Repeat the process of adding and lightening layers until the layer appears all white or all black.
Add timing to the animation. Navigate to the "Layers, Channels and Paths" box and double-click on the top layer. Place your cursor at the end of the layer name and type "(ms)." Before "ms" write the desired delay, in milliseconds. For example, to create a two second delay, write "(2000ms)." This creates an animation where the top layer image flashes for two seconds.
Double-click on the next level inside the "Layers, Channels and Paths" box. Add the delay by typing "(ms)" and adding the exact number of milliseconds before "ms." Repeat this process for the remaining layers.
Click on the "File" menu and scroll to "Save As." Enter the desired name in the "File Name" field and select the "GIF" option from the "File Type" menu. Press "OK."