There are many sources on the internet where you can download free music. These websites are easy to find. Just type "free music" in your browser. The more specific you are the easier it will be to find exactly what you're looking for.
As an example, let's say you are looking for a particular song. Type in the name of the song. If you know the arranger, add that as well. You will be taken to a website with a list of songs. Your song will be there. After you locate it, click and your song will come up.
Be sure to signify whether you want piano, guitar, vocal or such.
If you are looking for CD music, it's harder to find that without a charge. I like "I Tunes" as the cost is very minimal and they have an outstanding selection.
I hope this answers your question. Actually, you should be a little more clear about what type of music you want for free. :)