1. I navigated to http://last.fm/api
2. I immediately found http://www.last.fm/api/feeds
3. From there I found http://ws.audioscrobbler.com/1.0/user/CGamesPlay/recenttrack...
4. I guessed, and found http://ws.audioscrobbler.com/1.0/user/CGamesPlay/recenttrack...
5. The documentation on http://www.last.fm/api/show/user.getRecentTracks includes info on how to fetch scrobbles during a given time period.