First, you should discuss what source(s) you used to gather or generate the data for this project. Don't simply mention them, consider them, as you would an historical source. What is their validity? Is there anything you might need to be critical of when examining the data? To see an example of someone thinking about a source, see here.
Second, you should outline your methods in this project. This should can include everything from how and why you gathered the data. Also include any choices you made in modifying, editing, or cleaning the data.
Similarly, if you made a decision to use certain kinds of methods, this is where you justify it. Why did you use text analysis? Why did you use that specific tool for it?
In short, this is where you can justify why you did what you did.
For an example methods page, see here.