The final control is the Finish and will be marked by a circle within a circle. At the Finish, make sure you dib (if it's SI), and then walk back to the Download to retrieve your split times. If it's a Card Punching course then hand your control card to the person manning the Finish.
If you've been dibbing then remember to download. You dib a box next to a computer to download your course data. Usually you will be given a print out of your split times so you can see how fast you went from each control. There may be some preliminary results up around the download station, although the final results will only be available once all competitors have completed their courses. Results will be published on a club's website.
Once you have downloaded, if you have hired a dibber, please remember to return it.