If you've taken a good look and decided that:
then the next step of evaluating your source is asking:
Great! Start reading and taking notes.
It is crucial that you understand what you read, especially since you are reading it in order to write about your findings. You cannot write about anything competently if you do not understand what you are saying.
All that may sound obvious, but sometimes when we are under time pressure and know that we must use outside sources in a paper, we are tempted to just copy and paste something out of desperation. Don't do it! Even if you correctly cite this copy-and-paste passage (if you don't cite it, that's plagiarism), you will not be learning and you will not be writing well if you take that course.
Don't worry, you can either find a different resource that is both credible and relevant or if you really want to use this one:
Figure out why you don't understand it yet.
For these problems, doing a little background reading should help, and once you've gained the vocabulary, concepts, and contexts, you'll be able to understand it better. Reference articles, book introductions, some news articles, and articles written for a general audience and published by reputable periodicals are great places to start.
For this problem, you would need a lot of time to be able to deal with this text.
In this case, it may be better to find a different credible, and relevant source. To help you find a different source, consider: