From the My Documents section, click the "Request Confidential Letter of Recommendation" link. Enter the name of the writer and give your letter a unique title; this title will be visible to the writer as well as to receiving institutions you include in deliveries.

Next, indicate whether you'd prefer to email the request to your writer, or to print out a request form and physically give it to your writer. 

The writer submits your letter either by uploading it or mailing it to Interfolio.  When Interfolio receives the letter, it is converted to .pdf format and saved to your account. You will be notified via email that it is available for you to include in deliveries.