Hi Jim,
When you zip your skin for upload you need to be sure that the main skin is not zipped inside a folder. In other words when you unzip it, the files will go automatically into a folder with the name of the zip file. This folder is created for you by DNN.
Most, of the samples with skins included in the package do not have the preview images. But those are just a “nice to have” on your finished skin and not a requirement. The samples also do not use HTML skins with Tokens, they are .ASCX skins that do not need to be uploaded and converted.
The good thing about using the .ascx skins along with CSS is that you can just copy the skin folder to the “skins” directory of any portal and it will work. No zipping & uploading required, plus you can copy/move them to different folders without breaking them.