After learning about the Eluvian in the Circle Tower, you will have to head to Cadaish Thaig and caves near a Dalish camp (if you played the Dalish Elf origin, you'll know all about these caves). In Cadaish Thaig, there are four writings to look out for. Once you have all four, the achievement will unlock.
Worn Note - After crossing the fourth bridge in the Thaig, you’ll fight a group of darkspawn led by a Hurlock Alpha, head around a path to the left. It’ll be in a chest near a campfire.
Worn Journal – After finding two of the Lights of Arlathan, there will be an open area where you will fight more Darkspawn. To the right, is a little alley with a pile of bones at the end. The journal will be here.
Torn Letter – Near one of the vortexes used to find the Lights (off to the right side), there will be another pile of bones near a few large boulders. The letter is in the pile.
Scrap of Paper – After crossing a bridge, there will be a vortex. To the left of it, will be a scrap of paper stuck on a stake. Coincidentally, it’s called the Scrap of Paper. There’s the last of the lore.
Here's a video showing the locations made by bblnx: