You will receive a "finding" letter in the mail that will inform you when you should first certify for benefits. On the assigned date, go to the IDES website and click the link for "File Certification" in the top-right corner for the online UI services.
Select the option "File My Certification" near the bottom of the page. You will be prompted to login, which requires your online username and password (if you don't have this information, there is a short registration process to obtain it). After login select the option, "Claim Certification" and proceed through the questions.