The text and videos linked to below from the Canoe Slalom Technique Library explain this stuff well so there's no point me adding more here! You can buy a copy of the DVD, which has gates on it too, if you fancy learning a bit about slalom. Slalom is great for learning efficient boat control, do it if you can!
Reverse/bow draw pivots
Bow draw pivots
A drill for bow rudder practice
And some tips for goalkeeping
If you are having trouble with this stuff, go to a canoeing session and ask someone to help, there are plenty of people with the knowledge there so make use fo them! Star tests are a good way of making sure you know the range of strokes and how to do them correctly. The key is to practice things you are bad at, even if it makes you look like a mong, because that way you will eventually stop looking like a mong instead of avoiding the issue!