Usually, when we talk about evaluating sources, we mean that you should look for signs of quality and credibility: is your source peer reviewed? Do you know who wrote it and where it came from? Is there a clear bias or frame being presented that distorts the facts?
Good news! For this assignment, you can ignore a lot of that. Instead, you'll want to primarily evaluate your source for fit.
For this assignment, the most important thing to keep in mind is whether the retelling you've found fits your need. Things to ask yourself include: