There are similar questions on this forum already but I will try to answer your question:

The skins are just different background images. The components (scene, thumbnail, map, text, buttons etc) are placed on top of this "layer".

So creating a skin (or any related skin graphics) is a simple process: Use any external (third-party) graphic software (Adobe Illustrator or CorelDraw for example) to create your background - add any fancy frames, graphics, images, or logos that you like and save this as a .jpg, .bmp or .gif file. Remember to size your graphic to suite your tour (for example 800x600 pixels).

This can then be applied to your project using the 'Background Image' option in the Main Window Properties section (bottom of screen).

Try taking a look at the example Green Land tour skin that you get with TW. Look in C:\Program Files\Easypano\Tourweaver 3.00 Professional Edition\Skin\blue.skin and you will see all the image elements for that project. (Note: the path may vary slightly if you do not have the pro edition).

Have fun!

There are several good graphics programs out there for creating skins, it helps if the program supports layers, such as Photoshop.  Not sure, but does Photoshop LE support layers?  I'm working on a custom skin for a local Irish Pub here in town, you can see the test site at: http://www.your360virtualtour.com/Tours/mcguires_pcola/
I'm currently waiting on the manager to pick the 6 of 12 360's he's going to use, then I'll finish the bottoms and any scene descriptions.  The top banner of the skin is actually an edited image from the side of their building.  The colors were chosen to match their new site they are designing (working in cooperation with their web designer).  Since he's doing the site, I've got to match my colors to his. I think it's rather orange, but that seems to be what the owners and manager like.

Yeah, Photoshop is probably one of the best to use (but comes with a high price). As a least cost option you could use Windows standard Paint Tool. Techsmith "SnagIt" software could be used as well. Although it is a (very) good screen capture program, it also has a graphic editor built in so you could design basic image backgrounds - just not so fancy. Even Corel Painter (or Painter Essentials) can be utilized (this might give you some interesting "real" paint options) - they all output image files (jpg, bmp, gif).

I came across this link as well which will help loule:
http://www.easypano.com/showkb_118.html