There are several ways to make money from the money you already have. Some of the more popular financial tools are savings account, CD (certificate of deposit), Money Market fund, 401k, Regular IRA, and Roth IRA. Your earnings from a 401k, and the IRAs generally depend upon how the stock market performs. Your earnings from a savings account, CD, and Money Market fund are generally based upon compound interest.
Method number one will show you how much interest you can earn by investing a little each month from what you earn on the job. The second method shows you the same thing but with the help of an initial deposit. The third method shows you what you can earn by depositing a lump sum of money and letting it earn interest.
If you are a young family with children you probably receive a substantial income tax refund each year. Just for fun, why don't you see how much money you can make by putting it into a regular savings account and adding ten or twenty dollars to that amount each payday. Use the number two option to see the results.