WotLK I can not enter the icy chambers (pit, forges and chambers)

[Nacor0808]

I need to know how much of gearscore I need or what mission I have to take to go where these three dungeons are, because I have reached the maximum level and I have 2.5k of gs and I can not enter. I would like to know if it is some mission or amount of gs or what happens, because I do not know what to do (forgive my ignorance: /)

[phoinex9]

theres a quest to be taken from sylvannas who stands in front of the dalaran bank. This quest enables you to enter forge of souls