i’ve never played the guitar before, so i dont know much. one of the strings is practically clean off and is only connected to the tuning pegs. it seems alright otherwise, but, once again, i dont know much!!
The first thing to do is get a new string, or preferably a complete set. From your picture it appears to be a nylon string guitar so do NOT put steel strings on it. Steel strings will ruin the neck.
Then go to justinguitar.com and start from lesson 1. It’s a free site. There are certain advanced courses that you have to pay for, but starting out, all of the info you need should be free.
Good advice, http://justinguitar.com/ is very good and most informative. If you take the guitar to a music store, they will probably string it for you if you buy the strings from them first.