How can I review my current and past contracts?

You can find your job history by accessing the My Jobs page.
     

There, you can find your Active Jobs, your Completed Jobs, and even the Job Offers that you still haven't accepted.
     

On the Active Jobs tab, by clicking on each active job's name, you can access all the information about the job: work log/Milestone(s), earnings, and messages and files exchanged with the client, as well as the information about the client.