A good Complete Beginner Guide?

Hi all, as the title says I am a complete noob. I have played a couple hours of different arpgs here and there but new to diablo and certainly new to this type of end game gear stuff in a game (I mostly play narrative rpgs)

I would love a good guide for things in general but specifically I feel pretty lost on gear. It seems like there are so many systems for enchanting, slotting in jewels, managing unique stats from legendaries, and I don't understand if i should be keeping gear below legendary at all and on top of that if I should be selling or salvaging.

I am level 60 with 16 levels in paragon right now and I just haven't upgraded, tempered, or jeweled any gear because I feel like I have no idea what I'm doing.

I'm sure some of this sounds like very basic info but my history with gaming is mostly "higher rarity = better". I understand that what things you save or throw away depends on builds, but I'm trying to figure out what the actual variables that determine saving or salvaging/selling an item are.

Thanks in advance! I'm really loving diablo 4 way more than I thought I would so far.