In cell A1 go to Format, Conditional Formatting.
Under Condition 1 choose Formula Is and type =row(a1)/2=int(row(a1)/2).
Click Format, click the Patterns tab, choose your shading colour, click OK
and click OK again.
Copy the format to all the other cells.

"drummergirl73" wrote:

I used to be able to do this quite easily in Lotus 123 eight years ago. How
can I do this without having to individually select alternate rows to shade
in a large spreadsheet?