Here are the steps to host a Picasa Album directly off your desktop:
1) Create a Picasa Album
2) Export it as an HTML (Use "Export as HTML Page" menu item that appears on right-clicking on the album in Picasa) into a directory on your PC. Good idea to create a new directory.
3) In Purplenova, do Host new-> Host Folder, and select the directory into which you have exported the Album.
4) The folder (directory) shows up in the main window of Purplenova. Open it, and locate index.html. Right-click on it to copy its URL. Your friends will be able to view and navigate your album with this URL over the Internet.