Know the basics of playing the piano. Start by learning the layout of the piano keyboard and the notes that correspond with each key. You can use the manual that came with your piano or an online source.. If you are not an experienced player, this basic information will allow you to play a basic tune to get you started and keep you motivated to play more and enjoy the process.
Learn some simple songs. Start with basic tunes you enjoy and can easily play with a few piano keys. If you have difficulty thinking of songs to choose, ask yourself what you hum when you are in a good mood. Often that song will be a childhood melody or commercial jingle you can play to lift your mood. Especially if the song is a childhood lullaby, you should be able to find a list of notes that tell you what keys to play on the piano. For example, "Mary Had a Little Lamb," is played with the note sequence E-D-C-D-E-E-E. Look online or visit a music store to find reference material for certain songs.
Set time aside for yourself to play the piano for your own enjoyment. You can do this whether you are a talented pianist or just beginning to play. In that set time, play however you want, for your own enjoyment. You may wish to experiment with the keys, create chords or make up your own tunes. If you choose, you may even sing along and make up your own lyrics.
Find like-minded musicians to play with. You are likely not alone in your quest to play music for pleasure. Consider getting together with other individuals at a similar musical level and who share a desire to play a certain style. These individuals can be members of your family, friends or acquaintances who would enjoy playing music without the pressure of performance. They can be vocalists, guitar players, flautists or even rattle shakers; the key is that they, like you, want to play music for pleasure.