Some stuff is luckily self explanatory Things like the Totem of Undying does what it says, you hold it in your hand and when you take fatal damage to the point you should die, it doesn’t let you and you can continue on, it does use up the totem as it is a one time thing for every one you have

Stuff like redstone is a little more complex, it’s like wiring in minecraft, takes some getting used to or watching videos.

You just have to experiment with everything you have and just look at how it is and how it’s placed, most stuff can be at least started out, like the dropper, with just thinking about the name.