The Datasheet option is accessed from the Report Menu
Selecting this option will produce a Datasheet Report after you have select the data you require from the Data Selector Dialog Box.
The Data Selector Dialog Box for the Datasheet Report allows you to select data from a Time Date Range, the Last 24 Hours or the Last Week. It also allows you to select which Weather Station Channels include in the Datasheet Report.
see Using the Datasheet Report