Creating

There are lots of ways you can create a new workbook.
When a new workbook is created the name of the workbook is displayed in the title bar at the top.
If the name of the workbook does not have an extension associated with it, then the workbook has never been saved.
By default every new workbook consists of 3 worksheets although this can be changed by selecting (Tools > Options)(General tab, Sheets in new workbook).

File > New

You can create a new workbook by selecting (File > New) and clicking on New.

Shortcut Key

You can also use the shortcut key (Ctrl + N).

Quick Access Toolbar

You can use the button on the Quick Access Toolbar

File Explorer

You can also create workbook from Windows Explorer by right clicking in a folder and selecting (New > Microsoft Office Excel worksheet (this should say workbook ?).