In Android Studio, choose File > Open... and select the fresco folder.

Fresco uses native code for a few features. To build Fresco you'll need to specify the path to the NDK.

In Android Studio, go to File > Project Structure and in the dialog set the Android NDK location. Android Studio stores the NDK location in to your local.properties file.

The Showcase app is probably the best one to get started with. Select the Showcase app and click run:

You can use the drawer to select one of the demos: