The atlas linked above is truly beautiful, but I found its companion book Spectroscopy for Amateur Astronomers extremely informative and affordable.
Like OP, I'm doing visual spectroscopy with a refractor, and am also an "armchair spectroscopist." The book dedicates 40 pages to various spectrographs, equipment and recording/processing/calibration that won't be immediately useful.
However, it concisely explains spectral phenomena (briefly at the quantum level), your grating, the relevant details of human vision, and many important discoveries of modern astronomy (should you wish to re-create them or contribute data to research in the future). The chapter on the spacetime lattice is fascinating.
Edited by Enkidu, 21 November 2019 - 08:59 PM.