I will not say anything about controllers, only keyboard and mouse.
First off, healing is done using Q, Q will consume health packs(visible near the health bar). Healing using Q is really helpful for quick and easy healing.
Your inventory is opened by pressing F, you press F again to traverse the slots, then wait for the window to disappear for the item to be equippedl, then you can press LMB to use it, and to equip a gun again, you need to move your MMB.
Your items re equippable the same way as the former shown but with E, your items consist of grenades, bombs and herbs.

Be sure to know the settings you need to change.
My personal advice is to turn the brightness all the way up since it is mostly incredibly dark in a way you will stumble into unseen objects and may not find your way to the objective.
If you are new and want a relaxing experience, be sure to change these following settings:
1. Change Agent Hunt to Off.
2. Change game mode to "Playing For Fun", so you wont be matched with speedrunners or any of the other modes' players.

You have many things to watch out for in RE6.
1. Zombies lying on the floor, they can pull you in and trigger an escape qte tat might cause damage, all you need to do is step on his head.
2. Ammo, as in every RE game, is scarce and you will need to look for it in boxes and on zombie corpses.
3. Skill points. This one is a special addition to RE6 and it is used for skills which are purchasable in the menu of the game.

Thanks for reading, I hope you enjoy my guide!