Some common stops: 1. Snow-plow stop
2. T-stop
3. Hockey stop
Generally, when you stop on ice, you would scrape up 'flakes of ice' which would slow you down to a stop.
Snow-plow stop is the easiest. People do one-sided snow-plow stop most of the time that is stopping with one of your skates and not both. Just bend your knees, straighten one of your legs placing pressure on the inside edge of your blade of your stopping foot. You will scrape up some ice and eventually come to a stop.
T-stop is a little harder where you place on of your stopping foot behind and perpendicular to your skating foot to form a T shape.
Hockey stops are the hardest to master. You can look at this video here: http://www.youtube.com/watch?v=DTh7-lOagJU
And this video shows a backwards snow-plow stop: http://www.youtube.com/watch?v=YXicevWT8qI
And also, you don't stop with your toepicks at all. They are only used for jumps in figure skating. you put pressure on edges of your blades to stop.
You may also want to try this site: http://home.pacbell.net/anamga/intro.html#Basic%20Skating
It provides many useful tips on basic skating moves such as stops as well as advance moves.
Good Luck! =)