I would avoid "free" horse until you get a lot more experience. No one gives away a well trained, sound, beginner safe and dependable horse. The general rule is that free horses are project horses. In fact, anything under 1000$ is generally a project horse.
Before you get a horse, get a trainer and take some lessons. If you're asking these sorts of questions, you are not ready for your own horse. Even after you get some experience, get your trainer to look at horses with you. All of this will take time, and money, but you will avoid getting hurt or ripped off.