Answer:
Canasta is remarkably similar to a popular game that people play called "Hand and Foot," so if you know that, you should be able to pick up Canasta like a breeze.
A link to one set of rules is included in the related links area. Although, as with many card games, there are quite a few variations of rules, so if you find that this isn't the version you are familiar with, check out some other sites to find a different variation.