If you do want to produce your own worksheets and don't have the Microsoft software, you can download free tools like OpenOffice or use an online word processor or spreadsheet such as the free Google Docs which help you do similar tasks. You just need to create a table with as many rows and columns as you need and then type in some numbers before printing it off for your children to practice _ depending on the level of complexity choose single digits or multiple digits. If you're not sure what level to start at, aim low, start with easy numbers and see how your child goes, the self_esteem boost they'll get from acing the first worksheet will give them confidence for more difficult math problems.
Your aim should be to make math fun for your child and help them gain a solid understanding of the basics. Encourage your child to incorporate math into their daily activities, help them do mathematics worksheets, and then use the lessons therein to create fun activities for your child. The secret to learning math is to have an open mind about it. Just because you hated math doesn't mean your child should, and you will be doing them a disservice if you pass your negative feelings on to them. Make learning math fun, get a comprehensive set of mathematics worksheets to make it exciting and stimulating, and encourage your child's efforts all the way. Every math genius had to start with 1 + 1, just like your child.