Open a new browser window and navigate to your Wimpy Installation folder.
You should be presented with a list of files.
NOTE: Some web sites are configured to NOT automatically list the contents of folders. If this is the case, you will have to manually type the URL to the skin file you wish to use.
Click the "skins" folder to open the skins folder on your website.
Skin files are "XML" files.
Click on an XML file for the skin you wish to use.
When you click on the XML , all you will see is a bunch of code, this is OK.
Copy the address out of the browser's address area.
Paste the URL to the skin file into the Customizer's "Wimpy Skin" field.