If you have followed this tutorial here:
http://www.13dots.com/forum/index.php?showtopic=1596 then your ready to begin this
1) Make a selection like in the picture:

2) Fill it white

3) Duplicate the layer: layer -> duplicate layer...

4) Move the planet to the top of the layers...
http://img41.exs.cx/img41/7363/chazza-Pic4.jpg
5) Duplicate it, and move it to the bottom (above the background layer...
http://img41.exs.cx/img41/706/chazza-pic5.jpg
6) Merge it with the background layer...
http://img41.exs.cx/img41/8626/chazza-pic6.jpg
7) And merge one of the circles with the background layer too...

8) Then do a lense flare on the background layer like shown in the picture...