You can read my unofficial user guide at https://fedi.tips
Don't use Twidere, it hasn't been updated in over 2 years. It seems to be abandoned.
If you're using Android, try the Tusky or Fedilab or Toot! apps.
if you're using iPhone/iPad, try the Toot! or Ice Cubes or Ivory apps.
(There are also lots more good third party apps, but don't want to overwhelm you!)
You don't need separate accounts for separate servers. Just sign up on one server and use that account on an app.