If you've collected this non-combat companion, you can follow the steps detailed in the #secret-progress channel on the Secrets server to get caught up. Note that there are spoilers!
Alternatively, check out this [url=http://www.wowhead.com/uuna-storyline-a-dark-place]Wowhead guide[/url] for a detailed walkthrough.
PART 1 Process (taken from Secrets Discord), TL;DR version -- you'll need to perform the following steps in order (she has dialogue when you've correctly completed each step):
- 1. Summon Uuna out. Wait until she emotes/says something and then target and emote the following: /whistle, /roar, /cry (for some players, it's unnecessary to wait and the whistle, roar and cry emotes can be performed immediately)
2. Take Uuna to A'Dal in Shattrath.
3. Take Uuna to Lake Falathim (Western Ashenvale) and stand in the beam of moonlight.
4. Take Uuna to Nuu. It's a blue ragdoll located on one of the floating islands in Mac'Aree. Need to glide to reach it. She'll pick up the doll.
5. Take Uuna to Bloodmyst Isle and stand near the table where Jessera of Mac'Aree is. She'll pick up the wand.
6. Take Uuna to Shadowmoon Valley (Draenor) - coords are 56,41. She'll wear the flower crown. Wait for a few minutes before something terrible happens to Uuna. T_T
7. Kill your character and talk to the Spirit Healer to find out how we can find/help Uuna.
8. Head to Emerald Dragonshrine in Dragonblight and click on the black crystal inside the eye socket of one of the dragon skulls (eastern wall of the shrine).
9. Transported to 'A Dark Place' scenario, you'll find her. Target her and /cheer, and then place down a campfire.
10. Soul Eaters will come out of the shadows. Run into them to push them back. More and more will appear, getting closer and closer. Don't let them touch her. She'll start wanding a few of them that are close to chase them off, but eventually will cry out that she can't do it. Target and /hug her (I found a macro to /hug helps).
PS: Immediately after Step 6, Uuna cannot be summoned out anymore. She still appears in your Pet Journal, but you receive the error, "Uuna is missing" when you try to summon her. This is likely temporary, or at least until you find and save her.
You've saved her! But wait, there's more!
- 1. Vale of Eternal Blossoms - the wall (8,58)
2. Suramar - Nighthold entrance (uninstanced, 62,83)
3. Dalaran - Krasus Landing (Broken Isles, 74,46)
4. Dragonblight - Wyrmrest Temple (57,54)
5. Mount Hyjal - near Keeper Remulos (59,24)
6. Kun Lai - Everest Pinnacle (44,52)
7. Burning Steppes - inside Blackrock Mountain (38,67)
8. Shadowmoon Valley (Draenor) - Temple of Karabor (70,46)