Where's my purple hextech chest?

So I started playting yesterday and i saw the "looting and crafting inventory" button. I got to know that i had to get to lvl 5 to be able to open that inventory and then i would receive a purple chest with a skin, a ward skin and orange essence (my cousin plays LoL too and he told me that) but when i got to lvl 5 (my current lvl) I didn't receive any chest. Can someone explain me that?