I saw people mention about "Ad sets" and saying that they ordered 2 ads per set.
However, I couldn't find any fuction to add another set on the facebook ad tool.
By organic search, I found out there was something called "power editer" which just ampified my confusion.
How do I add an additional ad set on my order and what's about all this power editer thing?
Does it work differently from the ad tool on facebook ?
You can quite easily add more ad sets to your campaign, there's always a button in the same place for campaigns/ad sets/ads:

If you tick the checkbox next to your ad set you can also do a "Create Similar Ad Set", which duplicates it.
FB has really well-written guides on setting up campaigns and getting the hang of the Ads Manager.
The power editor just makes your life easier when you want to launch/manage lots of campaigns and it gives you slightly more precise control over everything.
Don't worry, it's all pretty simple once you get the hang of it. Here's some homework for you to read:
Power Editor Basics
Ads Manager Basics
shishev hit the nail on the head. I'd highly recommend reading more from the start by the sounds of things:
https://www.facebook.com/business/ad...%20News%20Feed
Adespresso have some great, easy to read guides too.
Don't forget about all the guide's zeno posted, a year or so ago now but still a huge amount of relevant information.
Thanks guyz
reallt helped me out