It is based on Tufte-LaTeX classes. So it sets a lot of things in the margin, so you'll have everything related to an entry in the same place.
It provides three new commands '\diarytime', '\diarycite' and '\references'. The first command, '\diarytime', sets a new date in the margin. The second command, '\diarycite', prints the full bibliography entry for a reference in the margin.
The third command, '\references', prints the list of references for the current section. For this command to work, the 'refsection' environment (or the '\newrefsection' command) from Biblatex must be used. Simply put, it prints a list of references for all references used since the last '\newrefsection' command. It's totally optional, use it only if you want to have all references for an entry in the same place.
You can compile the document using make(1). Just type 'make' in the terminal and it'll build journal.pdf for you. Use 'make clean' to remove all TeX-related build files and use 'make clean-depends' to remove the automatically downloaded files.