This can be tricky because private companies are not required to release information to the public. However, there are ways to find information about private companies.First, use library databases: Privco, Mergent Intellect, and Pitchbook. They gather information about private companies from many resources and publish it so you can use it in your research and learning.
If the company databases are not conclusive enough, conduct your primary research using Factiva, which allows searching newspapers published in the hometown of the company.
Last, contact the company directly and ask them for information. Be sure to mention the data is for educational purposes. They may or may not give you the information you need.