Calc Guide

http://extensions.services.openoffice.org/ and installing them as
described in Chapter 14 (Customizing Calc).
Figure 6: Starting a new spreadsheet from a template
Opening existing spreadsheets
You can open an existing spreadsheet from the Start Center or from
any component of OOo. Calc can open spreadsheets in a wide range of
file formats, including Microsoft Excel (*.xls and *.xlsx).
From the Start Center
Click the Open a document icon.
From the Menu bar
Choose File > Open.
From a toolbar
Click the Open icon on the Standard toolbar.
Chapter 1 Introducing Calc 17