From a SharePoint list it is easy to find how you would export the list to a Microsoft Excel Spreadsheet, however it is not so obvious on how you go the other direction. You can import an Excel sheet and create a new SharePoint list but I am not aware of a way to append an Excel sheet to an existing SharePoint list.

To create a new SharePoint list from an Excel Spreadsheet

  1. Choose Create from an appropriate page, such as All Site Content
  2. From the Create page, select the  Import Spreadsheet option from the Custom Lists options.
  3. Type in a name and optional description for the new list.
  4. Type in the path and name of your spreadsheet or browse to the file with the Browse button.
  5. Click Import
  6. You can then choose the range type and the range values to import.  For a basic spreadsheet you can choose the default range type of Table Range  and select the one range in the range list.
  7. Click Import.