In order to obtain this achievement you need to collect all 8 Pages to escape.
Here are the locations the Pages can be found.
- The Portable Bathroom
- The Visitor Centre
- The Warehouse
- The Car
- The Jeep
- The Watch Tower
- The Water Tower
- The Tent
- The Canoe
- The Park Map
*Note* According to alot of people they are getting it by picking up 4-5 pages and then running straight at Slender*
Below is a video of me getting the Achievement so you can gauge a rough idea of how its done.