Check Out How to Use the Steam Workshop for Portal 2
It was just last Friday when the Portal 2 Perpetual Testing Initiative DLC trailer appeared, which featured Cave Johnson discussing what we can do to help Aperture. The PTI DLC features an easy-to-use level editor where anyone can create as many intricate (or diabolic) puzzles as they wish and then upload them to the Steam Workshop. Once on the Steam Workshop, any Portal 2 owner can download and try out your level(s), so this is a good way to show off your creativity. Recently, a video showing how to use the Steam Workshop for Portal 2 was released, and it covers all the details you want to know. You can see how to find maps, download them, and even rate them once you finish. Cave Johnson is featured in the video, although his dialog appears to jump in randomly during the levels. Hopefully that is just a bug of the beta version and is not representative of the final product.
The Portal 2 Perpetual Testing Initiative DLC will launch on May 8th for the PC and Mac. There is no cost to download, so remember to refresh Steam if the download does not start next Tuesday.