Just want to add a basic idea to the above advice: don’t be afraid to experiment. Obsidian is wonderfully forgiving. After all, it’s not as if there’s a relational database or other “big” tech behind it. That’s part of the beauty of it–it’s" just" plain text files and your OS folders.
It’s almost unfortunate that they chose the term “vault”. That makes it sound as if there is something complicated and highly technical going on, like encryption.
Right after downloading the app I jumped in and made some folders, copied in some text and image files, then also made some vaults, then played around. And fell in love.
This is the way software should be for the user. Simple, elegant, fun. Yet as effective as you want to make it, depending on the effort you put in.
But you can always go with something like DevonThink, and its large manuals 