To Save an Excel Workbook, you can choose the menu File->Save As.

This will display the Save As dialogue box.

You can enter a name for your file in the File name text field, and click the Save button to save the workbook under that name. You can use the Save in list box to find a folder to save your files in. If you are saving an existing workbook, using Save As will let you save the workbook as a new file with a new name.

Another way to save your workbook, is to click the Save button on the standard toolbar, or press Ctrl + S on the keyboard.

These actions will also reveal the Save as dialogue box if it is the first time you save a new workbook. If you are working with an existing workbook, and you click the Save button or press the Ctrl + S keys, any changes you have made to the workbook will be saved under its current name.