Search a reputable site for smartphone application advice, such as cNet or Wired, so that you find out about the most current music identification applications available for your operating system. Two cross-platform examples, as of November 2010, are Shazam and SoundHound.
Read the requirements for each application to identify songs, as they may or may not suit your needs. For example, Shazam requires a recording of a song in order to identify it, while SoundHound allows you to sing or hum the song into your phone for identification. When attempting to I.D. a song you hear at a club or while out shopping, this may be more ideal.
Navigate to the app catalog on your smartphone, and download your selected music identification application. Note that free and paid versions of these applications may be available, and that free versions are typically less feature-rich than paid versions.