Select it from the iTunes sidebar. You'll have to sign up for a 12-month subscription at $24.99. Tap the Subscribe button to get started. If this screen isn’t visible, click Store > Turn on iTunes Match.

A dialog window will pop up and open allowing you to type your iTunes username and password. After entering your credentials and clicking the Subscribe button, your iTunes account will be charged and iTunes Match will be activated.

After purchasing iTunes Match, iTunes will go to work gathering information about your iTunes library. This information will be transmitted to Apple in order to match your music with potential tracks in the iTunes Music Store.

iTunes will begin matching your songs against those in the iTunes Store shortly after. This process will take a while, depending on how many tracks you have in your library.

After iTunes has matched all possible songs in your library, it will begin uploading the remaining songs. This process can be extremely slow, especially if you have a lot of music to upload. We recommend leaving your Mac on overnight for this process.

Once iTunes Match has finished uploading the remaining songs, you will see this completion screen. Repeat this process for all of the Macs that you have iTunes music stored on.

With iTunes Match turned on, you will be able to launch iTunes and see the cloud icon next to the Library. Here, you are viewing all of your iTunes Match media. Click on any of the songs in your library to begin streaming them from iCloud.

To turn on iTunes Match on your iPod touch, iPad, or iPhone, navigate to Settings > Music, and turn on the options for “iTunes Match” and “Show All Music.”

After turning on iTunes Match on your iOS device, you will be able to see and stream all content from iCloud by simply opening the Music application. iCloud songs will be denoted by the small iCloud logo. These songs will play just like a synced song.