Get your API key <a href="https://mycloud.rackspace.com/">from your Rackspace Cloud console</a> (read instructions <a href="http://www.rackspace.com/knowledge_center/article/rackspace-cloud-essentials-1-generating-your-api-key">here</a>), then pick a container name to use for storage. This container will be created for you if it does not already exist.