A User's Guide to King David's Sefer Tehillim - Book of Psalms. Featuring the 10 Things You Need to Know About Each Chapter. Who were the 10 authors of Tehillim? What do the musical instruments look & sound like? Shimmush Tehillim - Which Psalms do you say for special occasions? What are the 50 Psalms in the Siddur? Every obscure phrase explained.