The manual for Studio One 3 is a separate living reference document within Studio One 3, that must first be downloaded and installed when you initially install Studio One 3. As new features are added the manual will be updated as part of any future maintenance updates to Studio One 3.
The Reference Manual can be found by opening up the program. Then select "Help" drop down menu and select " Studio One Reference Manual " and it will open.
If you have not yet installed the manual in Studio One 3, below is a link to assist you:
http://support.presonus.com/entries/68996850-Where-is-the-Studio-One-3-User-Manual-