First, go over the Peer Review Instructions here. It contains step-by-step instructions and a quick list of do's and don'ts.
You have one week to complete the review. You should give comments on the peer's draft using the review or commenting function of a program like Microsoft Word, Preview, or Adobe.
Complete the Peer Review Worksheet by making a personal copy of the document, saving it as a new file, and filling it out.
Then submit your copy of the worksheet here.