Spotify is a free music streaming software and their goal is "to help people to listen to whatever music they want, whenever they want, wherever they want", you need to create an account on the sign up page with your usual details then once done, download the desktop player, install and run to start listening to tracks that you pick.
The tracks you pick can be placed into your playlist and shared on social media sites like, Facebook, Delicious and Twitter, you can even collaborate on a playlist with friends.
The free version does come with ads but not as much as you might think and when you are listening to the music you pick it is not a high price to pay, the site offers ad free signups for a fee of course.
Click the logo to visit the site and sign up.
Once you have signed up and installed the software pick a song for my playlist,