1)...What you want to do is first make sure the names of the columns in your
spreadsheet jive with the names of the fields used by outlook when you write
emails. You can add a fake contact in Outlook, or view a current contact in
Outlook, to see what the important fields are named (for example, First,
Middle, Last, Nickname, Phone, Fax, Email Address).

2)...If all is well, in Excel, export the spreadsheet to a text file (comma
seperated), and save to hard disk or floppy.

3)...In Outlook, click the "File" menu, hover over "Import", click "other
address book", click "Text File (Comma Seperated Values)", browse to the .csv
file and double-click it.