Those are the steps for the T10 quest.

1.
To start the T10 you must go to the city Shattrath located in Outlands. Its easy to find in the Teleporter NPC.
You can find the book, North-east in Shattrath in a House on the second floor.

2.
the first quest you'll get is to buy some "Sweet Nectar" and "Smoked Talbuk" x5.
--> You can find these items in the "World's end Tavern" in shattrath near the book of xtremeness
-->and speak to Shaarubo (bartender)

3.
Global locations/eastern kingdoms/eastern plaguelands
-Go south from the locations you spawned and go to "Lake Mereldar"
-The artifact is on an island in that lake

4.
Global locations/eastern kingdoms/alterac mountains
-Go to the first building you see if you watch North.
-Enter it and you'll find the artifact

5.
Global locations/eastern kingdom/hillsbrad foothilss
-go east
-You'll find the artifact on a small hill near the village

6.
Global locations/eastern kingdoms/deathwind pass
-Follow the road down
-kill the birds for the items and at the end you'll see the artifact

7.
Global locations/kalimdor/moonglade
The easyst way to find thsi is just following the road to the end. The artifact lies in the east of moonglade, near the cave for T7.

8.
Global locations/ kalimdor/durotar
-From your spawn point go west and follow the road to the barrens.
-When you reach some big thorns with the creatures "Razormane Battleguard" (somewhere in the middle of the map) go north east
-You'll find a small house with the xtreme wanted poster

9.
Go north into the canyon and just kill all the creatures there to get the items you need to complete the quest.
After the killing return to the poster.

10.
Global Locations/kalimdor/Dustwallow Marsh
You must follow the road south and go east when you reach the village 'Mudspocket".
When You come in the area "The Wyrmbog" go south and you'll see the cave of onyxia
-Make a raid and kill the mobs + boss

11.
After killing onyxia, go back to the xtreme wanted poster

12.
Global Locations/Kalimdor/Feralas
-When you spawn in Feralas, just follow the road to the north untill you reach the "Twin Colossals"
-West of the road you'll see a lake, fish there for your putty's.
-If you got all your putty's follow the road north again, and after some while go west untill you reach the "Ruins of Ravenwind"
The Lionstatue is on the broken temple

13.
-Global Locations/kalimdor/Tanaris Dessert
-When you spawn, go east in the direction of Gadgetzan.
-In Gadgetzan, you'll see in the east a road. Just keep following that road and you'll come to "Steamwheedle Port"
-In one of those houses you'll find the Xtreme energy cube.

14.
-Go down from to the dock, and you'll find the "Xtreme Race NPC"
-checkpoint 1: North of the xtreme race npc
-Checkpoint 2: North of checkpoint 1
-Checkpoint 3: Under checkpoint 2 in the water. (Use a buff or a potion for Water breathing, you must swim deep)
-Checkpoint 4: Above again and swim to the 2 Ships (Swim east). Left of the first Ship (North) you'll find Checkpoint 4
-Checkpoint 5: Behind the first Ship you'll find Checkpoint 5
-Checkpoint 6: Now you must swim under the second Ship (South)
-Checkpoint 7: Next to the first Ship
-Checkpoint 8: Next to the second Ship
-Checkpoint 9: Next to the second Ship
-Checkpoint 10: Between the first and the second ship underwater
-Speak to the race Npc again

15.
Outland Instances/Hellfire ramparts
-Go South-East from your spawn point and you'll see in the distance Honor Hold.
-Fly above Honor Hold
-Now you'll see North-East a road, follow it untill you see on the left side a broken tower. Here you find the Xtreme Matrix ...
-Behind the other broken tower, you'll find some birds (Bonestripper Buzzard) kill one of them to get the controller
-Go back to the Xtreme Matrix (Broken tower near honor hold)

16.
Global Locations/Outlands/Zangramash
-You'll need 200k Gold in your bags for this quest
-The first vendor you can find in the village at your spawn point--> "Fedryen Swiftspear Quartermaster"
-The second you can find in the village "Orebor Harborage" its located near the Tunnel from Zangramash to Blade's Edge (located North near the pikes from Blade's Edge) The vendor is named "Timothy Daniels (The Specialist)"
-Now Fly to the Umbrafen Lake, its near the "Cenarion Refuge".
-The Mushroom is in the middle of the lake on an island.

17.
Global Locations/Outlands/Nagrand
-Go south-west from your spawn location and use your flying mount.
-Fly over Warmaul Hill, Forge Camp Hate and here FLY WEST over the mountains and you'll find the Zone "Twilight Ridge"
-You must find here the object.

18.
Global Locations/outlands/Shadowmoon Valley
This one is more a tricky one.
-You need to go to the East side of Shadowmoon Valley
-Then just keep going south, its under BT and it's big flying Rock that is sepperated from the map. "Netherwing Ledge"
-Now find for a cave, it is in the west from that "rock"
-Enter the cave and kill all the mobs and take those cargo
-After you're done, above the cave there is a small village, in some of those houses you'll find the artifact (Plane)

19.
Go back to shattrath to the book of xtremeness.

20.
You'll get a key to Tempest keep
-In Tempest Keep you'll get your next quest and just kill the mobs and the bosses.

21.
-Kill the End bosses (the 5 bosses are all in the same room)