Login to Fourwaves using the email used on the original form.
In your dashboard, select the Participant role and go to the Submissions tab.
Click on a submission. You can use the search bar to locate it easily.
From the side menu on the right, click Edit submission.
You will be redirected to your submission form.
Note: if you can't save your form, it is possible that the submission period is over or that organizers didn't give you permission to edit. Contact the event organizers if this is the case.