Gun Jesus, Ian McCullom has the best youtube channel for researching all sorts of historical arms. https://www.youtube.com/user/ForgottenWeapons
He started to make a series of videos called "How does it work" not too long ago, they are a great start.https://www.youtube.com/watch?v=rk8G5-cJvR8>cleaning
That's simple, just disassemble and oil your gun, that's about it.
US field manuals and regular gun manuals might have more on this sort of thing. Gonna link the murdercube archive, CIA niggers took it down some time ago.https://the-eye.eu/public/murdercube.com/Firearm%20Manuals/http://the-eye.eu/public/murdercube.com/Field%20Manuals/
And i guess just general gun-related channels like Iraqveteran8888, Hickock45 etc.
Vickers Tactical yt channel shows short, compact videos about specific firearms, so that could be helpful.
gif related is from https://candrsenal.com/
, they make daytime TV style of short 40 minute documentaries about guns from ww1 on youtube, but they also have these diagrams/animations which are really great if you are just getting into learning about guns.
I hope that at least something of this is useful to you!