You may need more specific information before getting started. Researching your American Indian heritage can be difficult. Here's a guide to get you started: https://www.archives.gov/research/native-americans/research-individual.html
Since Fort Laramie is a site operated by the National Park Service, I would contact Fort Laramie Historic Site directly: Contact Us - Fort Laramie National Historic Site (U.S. National Park Service)
Good luck in your search. Please keep us informed on what you come up with.