After the installation of SpreadsheetWEB a new menu item called "SpreadsheetWEB" is added to the Excel menu bar. It shows up in the top tab as a "ribbon". Opening this ribbon will display a screen identical to the image below in the Excel interface.
To start the Wizard click on the "Wizard" icon in the ribbon.
SpreadsheetWEB ribbon in Excel
SpreadsheetWEB's "Welcome Screen" will appear. Click the button "Next >>" to continue.
SpreadsheetWEB Welcome Screen
Furthermore, see the video tutorial for starting the conversion:
http://www.spreadsheetweb.com/VideoTutorials/Wizard/Features/Begin_Convert/