1. There are no zeros in the answers.
2. No number can be repeated in an answer.
3. Each empty square must contain a number.
The rules to Kakuro can be learned in a few minutes but it will take months to learn the strategies that can help you solve these puzzles. I have included a few basic strategies to use in solving Kakuro puzzles with some partial puzzles for you to apply these strategies. Once you have practiced some of the strategies you can also go to the beginner puzzles on this site.
Perhaps other Kakuro puzzlers will add some of their own strategies to this site so we can all learn from each other.
Now you know the rules go to the Strategies page and learn some solving skills. Have your Kakuro number combinations handy, they will help you solve puzzles too. When you have read the strategies you can go to the beginner practice puzzles section of this blog.