You'll receive a notification when it's time to complete your self-assessment. You can either follow the link in the email or log in to your PeopleGoal account and go to Reviews > Start self-assessment.
Make sure the first thing you do is save a draft so that the review form is saved in the system. You can then come back and edit your draft at any time, by going to Reviews > Your review.
Once you're happy with your completed self-assessment, click Submit assessment at the bottom of the form to send this to your manager. They'll be able to complete their manager's assessment and once that's done you'll receive the completed review back for your final electronic signature.