Here you will learn how to make a planet and stars with a sun. You could use the planet and stars in a banner or something, that would look pretty good.
1. So make a new document 500 x 500.
2. Hit D to reset your colors to black and white.
3. Hit Alt + backspace to fill the background layer with black.
4. Now we're going to create the stars. Go to Filter > Noise > Add Noise, and use these settings:
5. That's a bit too many stars, so go to Image > Adjustments > Brightness/Contrast and make Brightness -50 and Contrast 55. This looks like a good starfield now.
6. Make a new layer.
7. Now we're going to make the actual planet so go to Filter > Render > Clouds
8. Filter > Noise > Add noise with these settings:
9. Filter > Blur > Motion Blur with these settings:
10. Select the Elliptical Marquee Tool. It is hidden under the Rectangular Marquee Tool, just click and hold on the latter to reveal it. It looks like this:
11. Make a Circular selection about 200 px high by holding shift then clicking and dragging.
12. Filter > Distort > Spherize with Amount set to 100% and mode set to normal.
13. Now invert the selection by hitting Ctrl + Shift + I.
14. Hit Delete.
15. Hit Ctrl + D to deselect the selection.
16. Now hit V to select the move tool and move your planet to the bottom right of your pic, but leave it like 30 px or so from the bottom and right edges.
17. Now select the background layer by clicking on it in the Layers box.
18. Filter > Render > Lens Flare and make it look something like mine with Brightness: 140 and Type: 50-300mm Zoom:
19. Make a new layer above layer 1.
20. Ctrl + Click Layer one to get a selection of it.
21. Hit D to reset your colors.
22. Hit X to reverse your colors.
23. Hit G to select the Gradient Tool.
24. Now draw a radial gradient across the planet like this:
25. Change Layer 2's blending mode from Normal to Multiply.
26. Select the planet layer. (Layer 1)
27. Hit Ctrl + U to bring up the Hue/Saturation Box, and use these settings: Hue: 16, Saturation: 60, Lightness: -10. Colorize: Checked. Click OK.
28. Now you should have something like this. I added an astronaut and a space shuttle because it would be funny.
More Tutorials: 
I tried following the instructions that you gave but when I get to the "land" layer and than ctrl (click on water layer) and than try to spherize it will not let me unless I put something in the land layer. You left out something when you got to the land layer part. I will read the forum and see what I can find.