Activision & Treyarch released a tutorial about how to really use the Black Market system in Call of Duty: Black Ops 3. Learn how to utilize the Black Market system...
When you got your item from the Black Market, pay attention to the item, and what it's for - it shows at the bottom. For example, if you got a skin for your gun, go to your loadout and look at your weapon a dialogue will appear, and with a green arrow next to the button prompt.If theres any help to be gotten it seems to be here. Once i exchange the kryptokeys and get the drops ive gotten some cool stuff. but after that it never shows up again on how to use these items. Like i said i've gotten a lot I want to utilize but i don't know how to add them to my player or class. Please please any help would be amazing