The Reference Manual is a multitude of information about Quantum, especially documentation of user functions defined in Quantum.  It assumes you are already conversant in the Quantum language, since if you aren't, that is what the Learning Manual is for (enroll in Quantum University).  The Reference Manual is structured like a tree and contains 2000+ and counting topics.  However, unlike the Learning Manual, the Reference Manual is not such a great "read" from cover to cover.  The Reference Manual is more like an index, appendix, or small encyclopedia.  If something strikes your fancy, you search for the relevant topic(s) in the Reference Manual.  That is your best modus operandi with the Reference Manual.

P.S.: If you've read the Learning Manual and are still begging for something more to read, we suggest you try browsing the source code for Quantum's demos.  They are written in Quantum, not English, but should be profitable to you.

(NOTE: The Reference Manual is not available on the PLANETQUANTUM.COM website.)