The first step of the quest is very basic. Go to the Zoram Strand, stab members of the cult until they drop something noteworthy. It seems to have a rather high droprate, so don't worry too much. Once you've read the note (and I'll trust you read it so you don't need to reread it here) dig in your bags for the Totemic Beacon you were supplied with, and put it to good use. The neighborhood puppy will run up to have a chat, he'll hand over some Burning Blossoms and we move on to the next step.
In my opinion, this next step is one of the coolest things we've seen in a quest recently. Not only do you get an awesome disguise, but you're also in for a pretty sweet resolution to a loose storyline in The Burning Crusade. Before we get ahead of ourselves, head north. You don't need to use that Orb of the Crawler you were just give yet, but you can. If you're a high enough level to have a mount, you can ride toward the northern camp much faster and use the orb when you're there. However, you only get this thing for so long, so I crabbed it up the whole way up the shoreline.
The camp you're looking for is at the very edge of the northern beach, where the Strand bends toward the ocean. By the time you see it, you'll nearly be in Darkshore. Refresh the duration on your crab disguise, and approach Ice Caller Briatha and the Naga up ahead. Yes, you saw that right. Naga! Naga Heretics at that. What's the significance of that, you ask? If you have a level 70, you probably understand the conversation between the Naga and the Cultist pretty well. This is the conclusion of Skar'this the Heretic's story, and we finally learn his purpose. They're preparing to summon Ahune the Frost Lord, servant of Neptulon, in the Coilfang Reservoir. From there, they'll usher him into Azeroth to battle Ragnaros and bring about an elemental apocalypse. I thought we killed Ragnaros a few years ago, but hey, what do I know?
After returning to your capital city of choice and talking to the Earth Ring Elder, two new opportunities open up for you. The first is a quest called Striking Back. Wowhead lists multiple versions of this quest for various level ranges, but I've so far only been able to access the level 67+ version. All of them look roughly the same, so the strategy I am about to supply you with probably applies to them all.
Travel to your destination. In our case, it's Hellfire Peninsula. When you're looking at the Dark Portal, the Twilight's Hammer camp is directly to the left, behind the Legion forces. Walk up to one of the bright blue obelisks, click, and summon one of Ahune's minions. The strategy is thusly: HIt it until it dies, then turn in your quest. It is very, very weak for a giant elemental. This becomes a Daily Quest once you've completed it the first time, and the reward is 10 Burning Blossoms and 7 gold, 83 silver.
Your other newly available quest, Ahune, the Frost Lord, is fairly straightforward as to what you need to do until you meet Ahune himself. Go to the Slave Pens, talk to who you need to talk to, and follow the instructions. The strategy for Lord Ahune is quite a bit more involved than that of his underlings. Unfortunately, that will have to wait until another time. Until then, goodbye and good luck!