To leave feedback for a completed gig on the Gigwalk platform, a user should navigate to the completed gigs section within the app or website. Once there, the user can locate the specific gig for which they wish to provide feedback. Typically, there will be an option to rate the gig or leave comments based on the overall experience. Feedback is usually submitted through a rating system, where users can assign a score and potentially write a brief review detailing their experience. It is important for users to be honest and constructive in their feedback, as this can help improve the quality of future gigs and assist other Gigwalkers in making informed decisions. For specific instructions or any additional details, it may be beneficial to consult the current help section of the Gigwalk website.