First, you must make sure you are logged into Portal.  Then, click on Applications on the left and then eCert - My eCert on the right:

Then go to the correspondence tab. You will see a PDF icon next to your teacher certificate. Click the on the document name. The document name will be underlined when you hover over it with the mouse. Click on the underlined name and the document will open so that you can print your certificate.

Please note:  If your cert ID is not associated with your Portal account, you will be unable to access My eCert.  Please refer to Option 1 or Option 2 here to learn how to associate your CertID with your Portal account.