Plagiarism is a type of cheating. It happens when you use the work of other people and don't point out to your reader what you've used, who wrote it, and where you used it.
Your teachers know that you are using other people's writing to learn about your History Hall of Fame person. That is part of the assignment: to find other people's work, read it, and use it to make your own presentation. It's GOOD to use other people's work. In academic papers, the more you use other people's work and give them credit for it, the better and more authoritative your paper is. No one expects you to create new knowledge!
The cheating part happens when you don't let your teacher know what you used and where you used it. if you CITE your sources, you won't be plagiarizing.
When you find articles in the databases that you want to use for your project, use the citation tool in the database, copy the citation, and add it to your works cited list in Google Docs.