Put the song title in quotation marks. Follow up the song title with "by" and then the name of the artist (i.e. "Born This Way" by Lady Gaga). If you're making a reference to the name of an album, type the name of the album in italics or underline it if you are writing by hand.
Cite the song at the end of your book as a reference in Modern Language Association (MLA) format, which is the standard format used in English studies and book publishing. To do this, make an alphabetical list at the end of your book called "References." Start with the last name of the artist followed by a comma, then the artists first name followed by a period, and then the title of the song and a period in quotation marks. Next type the name of the album in which the song first appeared in italics (or underlined, if handwritten), followed by a period. Then write the name of the production company that produced the album followed by a comma and the year the album was released followed by a period. Lastly, indicate what form of music the song was on (CD, audiocassette, record, etc.) followed by a period (i.e. Morissette, Alanis. "Head Over Feet." Jagged Little Pill. Maverick, 1995. CD.).
Put song lyrics in quotation marks just like you would with any other dialogue if a character in your book is singing a song. For instance, if a character named Harry is singing the national anthem of the United States, you would write something like:
Then Harry began to sing "The Star-Spangled Banner" to everyone in the crowd.
"Oh say can you see, by the dawn's early light," Harry sang.
Song lyrics are copyrighted and thus cannot be printed in a book without consent from -- and usually payment to -- the copyright holder. Some songs (as well as other published works) fall into the public domain many years after the copyright holder's death, meaning that anyone can use or reference the copyrighted works without having to get consent or payment. To determine if the song lyrics you want to use are in the public domain, visit Cornell University's website devoted to copyrightand public domain. If the lyrics you want to use are still under copyright, attempt to contact the copywrite holder of the song you want to use to get their consent if you feel the lyrics are an essential part of your story. If they're not, it may be easier and equally effective to simply mention the title and artist of the song.