Unlike Ancestry.com, where each user maintains individual trees, FamilySearch has one "wiki tree" that everyone can add to and edit. When you enter info, you might find that your ancestors have already been added by someone else!
You can access MSU's Ancestry subscription through the library's databases page or enter the website directly (ancestrylibrary.com) if you're connected to MSU's VPN, using a library computer, etc. The library subscribes to both US and international records.
Hint: use your free family tree on Ancestry.com to get relevant hints, then use the library's Ancestry subscription to search and view the records!
Search Freedmen's Bureau records at the Mississippi Department of Archives and History. You can search by name, county, plantation, etc.
Hint: Simply searching Google for an ancestor's name can yield results from obituaries, full-text family history books in the public domain (from Google Books), and more. For best results, put the name in quotation marks, i.e. "Jane Brooks." Google searches work better on full names and less common names. To narrow results, include a state or city, i.e. "Michael Edward Stanton" Philadelphia.