Hello.
When I became lvl 70, I of course wanted to start to raid. And the first raid I think everyone starts with, is Karazhan. So I started to search a little, but I found it very hard to see where, and how I would get attuned to Karazhan. Ive seen no REAL guide on how to become, and that is why I decided to write a guide so others can get attuned more easily.

So lets start.

Note: You need lvl 70

How to:

Total instances you need to run in correct order:
Mana Tombs (to be able to loot the key in sethekk halls)

Sethekk Halls (to loot the key to shadowlabs)

Shadow Labyrinth (1st keyfragment)

Steamvaults (2nd keyfragment)

Botanica(1st key half for arcatraz attunement)

Mechanar(2nd key half for arcatraz attunement)

Arcatraz (3rd keyfragment)

Old Hillsbrad Foothills (to get attuned to black morass)

Black Morass (to combine the 3 fragments into the kara key)

Step 1:
First, you need to fly to duskwood(alliance), or swamp of sorrows(horde), and walk to the deadwind pass. In the deadwind pass, the Karazhan lies. If you cant find karazhan, just search thottbot for deadwind pass, and you will get a map over that place and see where its located.

Go to the front of the big building, and talk to the NPC. He gives you 2 quests, accept both, and do them.

Arcane Disturbances
Restless Activity

After youve done them, he will give you a third quest, which is the first quest in the actual chain.

Contact from Dalaran

Step 2:
Fly to southshore (alliance) or somewhere close to that (horde), and walk to the place where he sended you to. If you cant find the place, look the quest up on thottbot. This guy will send you to Shattrath, and the NPC you need to talk to is in the middle of the middle in Shattrath.

He will give you the quest for the first key fragment, which can be located in Shadow Labyrinth.

Step 3:
Can be skipped if you get a friend with Shadow Labyrinth key
In order to get the key to Shadow Labyrinth, you have to loot the key from the last boss in Sethekk Halls. But in order to be able to loot it, you have to have killed the last boss in Mana Tombs.

So start with Mana Tombs, and then do Sethekk Halls.
Now youre attuned to Shadowlabs.

Step 4:
Do Shadowlabs(Shadow Labyrinth) to get the first key fragment, and then turn in the quest. Accept the quest for the second and third key fragments.

Step 5:
Do the steamvault, where you will find the second key fragment.

Step 6:
Can be skipped if you get a friend with Arcatraz key, or a rogue with lockpicking high enough