How do you meditate when there are no instructions (only music) on what to do during the mediation?

i don't meditate, i don't know where to start but i'd like to. i think that can change my mind, i'm a person very anxious and stressed, not for a real reason, my mind start create problems everywhere for everything, i'd like to know how to stop it, maybe meditate can help me, maybe some mental and physical exercise like yoga can help my mind to over-think.