The catalog record of an eBook Central e-book will indicate "electronic resource" and its link will specify ""

After you click on the link to access the e-book, you can choose between "read online" and "full download."

If you select "full download" instead of "read online" or if you select the download icon within the "read online" toolbar, you will see a prompt to specify your type of device. 

If you do not yet have Adobe Digital Editions, you will need to download this program in order to proceed. 

You then can select a borrowing period of up to 21 days. If you are using a computer, the downloaded file will appear in your computer's download folder. 

You then can read your e-book offline, for up to 21 days.