Welcome to the obsession that is fanediting. If you haven’t already, you’ll want to research various editing software to see what aligns with your budget and editing requirements. There are free software options that can produce fairly straightforward edits along with industry grade (and priced) options for those that dabble into the realms of vfx and want to drastically alter films.
There are a few different communities with some fantastic examples of fanedits and editors; here, the other you mentioned as well as fanedit.org. Glean all you can and then jump in and get wet with the process.
“You’ve taken your first step into a larger world.” 😃