How do you convert a picture into grayscale in photoshop?

Open your photo into Photoshop. 
Convert to grayscale. (Image—Mode—Grayscale).
Done

Hope this helps. c:

The "maple leaf rag" (copyright registered on september 18, 1899)[1] is an early ragtime musical composition for piano composed by scott joplin. it was one of joplin's early works, and became the model for ragtime compositions by subsequent composers. it is one of the most famous of all ragtime pieces.[2] as a result joplin was called the "king of ragtime". the piece gave joplin a steady if unspectacular income for the rest of his life.

All of the above have been used in film noir.