Ask whoever admins your computer to install it. Or check http://msdn.microsoft.com/library. I don't know if msdn includes all docs, but look at the left pane for Office Solutions Development, then check under both Excel and Office. Then check http://office.microsoft.com.

About the object model, a quick google search shows several resources. The OM shows how each object fits into the heirarchy of all Excel objects, which objects are collections, which methods and properties are associated with which object.

Seriously, though, open excel, tools->macro->record macro. Then view the source Excel creates. It's VB code, and it is pretty easy to understand. It'll take you a little time, but you'll find it makes learning to write the automation code easier. Create the Excel object, open/add the workbook, insert translated and/or new code here, save (and save often), quit.