Read the paper: sigcomm.pdf. This paper is one of the foundational papers about P2P networks and DHT in particular. This will give you an introduction into the idea of routing and storage in a distributed fashion. In our P2P project we are doing a much limited version of this, but hopefully you can see the parallels! The summary should be a single page-ish (assuming it's single spaced). Focus your summary on a few aspects that you found interesting about the paper, you don't need to thoroughly walk through the entire thing. Keep it pithy!