You will need to get permission from the search administrator to update your application.  Look in your confirmation email for the contact information.

If you have received permission to update your application, log into the applicant portal.  
From the navigation panel on the left, select Your Applications:

In the Completed Applications section, find the application you wish to change and click on the Edit link.  

From the dropdown at the top, select the References section, and then click the red GO button

VERY IMPORTANT:
You must completely delete the reference you wish to change, and then re-enter it with the corrected information.  Although the system will let you edit individual fields, this can potentially damage your application submission.

Since you will be deleting the reference entry and re-entering it, you might wish to do a screen shot to preserve the information.  Then, click the “Remove Entry?” button at the bottom of the entry, and press Save Changes.

Next, click the Add Reference Entry button, which is under the last reference entry.  This opens a blank reference entry which you can populate with the correct information for the reference.  Enter in the complete reference entry with the corrected information, and press Save Changes.

Finally, you need to re-submit your corrected application.

From the dropdown at the top, select “Check for Errors and Submit”, and then press the red Go button

Click the Certify and Submit button

Click the checkbox next to the certification statement, and then click Submit this Application

That’s it – your corrected application has been re-submitted.