Playerunknown's Battlegrounds doesn't have any form of crafting - you can't create your own items by turning garbage into deadly weapons. Instead, the player has a simple weapon modification system at his disposal. The following guide section provides advice on how to upgrade your PUBG equipment.
You will find all the upgrades you can install while exploring the map. In most cases they will be located in buildings. These are often small items, so you should take a good look around to make sure you don't miss them.
You can install the found equipment in the inventory menu. It allows you to mount from one to several items that have a significant influence on the behavior of the weapon. Here you will find optical sights, silencers, handles and clips. All these, will allow you to customize your weapon to your individual needs.
You can open the inventory by pressing I or TAB. You will find there a list of items from your backpack, then a depiction of the avatar and the stuff it's wearing. The last thing is the section with weapons that you're wielding. You can simply drag'n'drop items from the inventory into the usable items fields - same goes for disposing of stuff you don't need.
Check out the slots underneath the firearms - there you can put different augmentations that will improve your aiming, accuracy or increase the ammo capacity of the gun. It's a sort of very rudimentary crafting mechanic. Weapon mods can be found in different parts of the map - collect them, because in case of long-range weapons more accuracy or more ammo capacity can mean the difference between life and death.