When sailing downwind approaching a dock can be a little tricky, if you have room to turn around go slightly past the dock then either jibe or turn 180 degrees till the bow is head to wind and all sails are luffing and the boat stops. When you are head to wind the boat will stop within it's own lenght. If you need to get closer to the dock back wind the jib to push the bow toward the dock. You might want to practice this with a mark or buoy, not in a crowded marina. I raced J22's with no motors, so getting back to the dock when the wind was behind me I used this method, another is to drop the jib before you get there, as you get closer have a crew member drop the main, have the bow line attached, steer close to the dock have a crew member jump out and stop the boat. Using this method make sure the main halyard runs free! You may need to drop that main quickly, if it hangs up you will be crashing the pier, no pretty.
It's a wonderful sport, learn, enjoy.
Pearson 28-2 "Lila"