You can go about this several ways. My prefered method is dragging everything out of the hot bar to get rid of it. Then using the inventory, character sheet, and spell sheets to put what I want where I want by dragging them into each slot on the hot bar.
For ease of use I put my healing potions, then my revive scrolls. After this if I'm playing a cleric I put my healing spells, healing word, cure wounds etc. Then my armor spells, followed by the spells I use to attack, next comes my buffing spells, then my actions (these use my channel divinity when I get it at lvl 2.) followed by spells I only sometimes use. Next are potions, then scrolls, and last is throwables. Anything that has thrown in their description tag.
For mages the first 2 slots are the same, followed by my arcane restore (that lets me get 2 of my spell slots back) then its the same as cleric without the actions (since wizard doesn't get channel diviity)
the same goes for pretty much all classes. Things I use most are on the top closest to the left of the hot bar. the further right I go the less likely I am to use them.
If you have any particular questions you can message me on the forum. I'll try to answer.
