A few old Bolsheviks wrote biographies that will give you clear, concrete details of underground activity. See "Twenty Years in Underground Russia: Memoirs of a Rank-and-File Bolshevik" by Cecilia Bobrovskaya
https://www.marxists.org/archive/bobrovskaya/twenty-years/index.htm
Are you reading the Science of Logic? It's not a good introduction to Hegel, let alone philosophy. Start here instead: https://www.marxists.org/reference/archive/hegel/works/ol/encycind.htm Also (cliche I know) browse around https://plato.stanford.edu/ for broad overviews on certain topics.
Contrary to everyone here I would encourage you to go further. Understanding dialectics is a necessity for any Marxist--here you will perhaps be interested in Lenin's Philosophical Notebooks. To really understand dialectics, and be able to make the transformation to its material ground would put you in a position to understand Marxism better than 99% of today's "Marxists"