5. Now create a new layer above the two previous, and call it "Background". Here you enter the background color or picture that you want. In this case I used a pergamenty type color.
6. Create two more layers above the background. The bottom one is "Countries Interior", the top one is "Countries Border". Set the Countries Interior layer to 10% opacity.
7. Now comes the fun part. Make the Background layer invisible, and go to the Countries Solid layer. Use the Fuzzy Select Tool to select the nations that you want to be the same color. Use "add to the current selection" to make sure that you have them all selected at the same time. You can do each country seperately, but it's easier to do them all together.
8. Go up to the Countries Interior layer. Using the Bucket Fill Tool, paint the countries in the color that you want the border to be. If you under "Affected Area" choose "Fill While Selection", you'll fill all the countries at the same time with one click. In this case I chose a dark green, which you might not be able to see, but trust me, it there is a difference when you turn the Background on.
9. Next choose the Airbrush Tool. Set brush to "Circle, Fuzzy 19". Depending on the size of your map, you may want a scale setting larger or smaller than the default 1. You might be surprised how large a brush you'll need, but if it is too small, you can always undo and take a bigger brush. For this 2000 x 2000 pixels picture scale 5 fit the bill.
10. Now change to the Countries Border layer, and chose Edit -> Stroke Selection -> Stroke with a paint tool -> Airbrush and click stroke.
11. Finally invert your selection and press delete to remove the paint that was outside of the borders. Your first batch of countries are all done.