cornelyj covered the answer better than I could have in words. The specific drills are a little difficult to describe in text, so I will show you a few video clips that demonstrate what basic active stretching consists of.
This clip below contains basic stretches that everyone should complete before exercising.
http://www.youtube.com/watch?v=ppg-ALSHEaE
The next clip below has a bunch of additional warm up activities that will help loosen muscles and raise your heartrate. The buttkicks and B skip drill are the most applicable to distance running. Thats not to say the other drills won't help, but I would consider them more for competitive runners.
http://www.youtube.com/watch?v=vcH97Dx8VCk
These drills look really silly, I know. But they are extremely helpful additions to any running exercises.
I hope this response helped!
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