How do I sort submissions in alphabetical order?

While viewing your submissions:

http://www.jotform.com/help/269-How-to-view-Submissions

Click on any columns header to sort that specific row alphanumerically.  You can also export you submission data to excel format for more specific sorting options:

http://www.jotform.com/help/44-How-to-Export-Form-Data-to-Excel