Hi @DARAPTURE07 and welcome to the forums!
You get an Apex pack every couple of levels. You get 45 Apex packs up to level 100. Other than that you have to buy them or get them via a promotion.
When you open the Apex pack you can select one of the items and click below on Equip to equip it.
Or from the menu screen you can go into the Legends tab or Armory tab and select your Legend or your weapon group. Then choose one on of these tabs: Skins / Banners / Quips / Finishers. Locate an unlocked item and select it. If it's a skin click on Equip in the bottom right-hand corner to equip the item. For all other items you just have to click them.
Some items can be crafted using materials earnt from playing matches.
Happy hunting!
