Finding primary sources can be tricky. Written primary sources may be found online or in print - in archives, on websites, and of course, the catalog. Books may be primary sources themselves (think autobiographies or accounts of events), or secondary sources that contain primary sources. Newspaper articles from a time or event can be great primary sources. Images and objects may be found in paid subscription databases such as ArtStor, but also in free online collections such as the Library of Congress (LOC) or Digital Public Library of America (DPLA). Below are some great places to start. If you are having trouble, don't hesitate to ask a librarian.
Image: Basketball at the 1936 Summer Olympic Games in Berlin. First appearance of basketball in Olympics. This stereograph is from the book "Die Olympischen Spiele 1936" by Heinrich Hoffmann (photography) & Ludwig Haymann (text). published by Raumbild-Verlag in 1936.
The websites below are good places to look for images of the Olympics. Please note that you should credit all images used in your project. A slide at the end of a presentation with a listing of the image sources will do.