Project surveys automatically generate an email notification with a link to take you directly to the survey. If you lose that email, or never saw it in the first place, (check your spam folder) you can always access the survey from Home or your project's surveys tab.
To access your surveys tab: click into your project, click on the Surveys tab and you will see any past surveys, as well as any currently due surveys with a Respond Now button. Click Respond Now to complete your survey.