Every cord has its own set of single notes that make them up. You can easily find out what these are online or in almost any music book. Once you learn them you will be able to play any song beautifully.
To play chords on a piano you will need to have your fingers relaxed and loose to be able to play multiple keys at a time. to start you will want to try out a C major chord which is extremely basic. Practice playing that chord to get your fingers used to playing piano chords.