For installing ribbon on almost all machines, it's recommended you set the ribbon selector to the "red" position and then simultaneously press the H and G keys so that they meet in the middle and temporarily "jam" in the up position. This holds the ribbon vibrator in its highest position making the vibrator easier to access and thread.

Reading manuals for your particular machine can help with respect to whether the ribbon should come off the front or the back of the spool: https://site.xavier.edu/polt/typewriters/tw-manuals.html

Reply to u/Smurf404OP at https://old.reddit.com/r/typewriters/comments/1mifdaw/why_is_it_so_damn_hard_to_thread_ribbon_through/

Royal Futura 800 Vintage Manual Typewriter Ribbon Change Install Magic Margin Demo by [[Phoenix Typewriter]]

A quick overview of the Royal Futura 800. Duane shows the very basics here including one of the simplest ribbon changes out there. He also does a quick overview of the Magic Margins, though it's not the best demonstration.