Activate windows 8 OEM?

ok, so i don't know much about the new OA3.0 or OEM activation in general.
but here's my situation:

i received a windows 8 gateway pc yesterday in the mail.
later last night, i tried to partition the hard drive using easeus partition magic, and but while the laptop was performing the partition, the computer restarted itself out of nowhere and windows said 'your system needs to be recovered.'
it said to insert my recovery media (which i didn't have) or my windows 8 disc (which i didn't have) or to contact support.
since i didn't have the recovery media, i downloaded a win8 iso and set up my usb drive to install it.
my hard drive needed to be formatted because the partition went wrong, and so i installed a clean windows 8 (not pro, my pc came with core windows 8) onto my laptop. now i have no idea how to get it activated again.

please help me

 

sorry COA stick? what exactly is that?

the problem is, i don't have any OEM key. i looked all through the documentation the box and there is no OEM windows key. it would look like XXXXX-XXXXX-XXXXX-XXXXX or something, right?

 

let me restart my computer and check under the battery

 

there is no COA sticker on my laptop at all, there is a windows 8 sticker on the bottom next to a sticker with the model/serial number. but there is no COA sticker on my laptop and there is no OEM key in the box

 

i've checked all over the laptop, there is no sticker. not even under the battery.
there is no recovery partition, i deleted all partitions and started fresh