ANNOUNCEMENT: New string policy!!
It is no longer my policy to repair strings as a courtesy to kids (exception: only my guitars if there is a defect). I have done this in years past, but there are just too many kids this year! Single strings are available at any music retailer (bring in the physical guitar so they can sell you the right strings) for about $1.50. Below you will find how-to videos to string them yourself! Classical guitars have nylon strings. Acoustic guitars have metal strings.
You can purchase guitar strings at Guitar Center or online through Amazon