The hardest part about looking for materials in the databases that contain primary sources is that you must search for them using the language from the time period. The English language has evolved; words that were common more than 100 years ago aren't used now and vice-versa.
When you are deciding what keywords to use, you might want to look at some of your class readings or other secondary sources to see if there are names of people, events, or other specific terminology that is mentioned.
Many books and other materials in the catalog may be primary sources. Trying using these keywords with your topic to search for them: correspondence, diaries, interviews, papers, personal narratives. For example, this is a search on the words George Washington correspondence .
Christian Recorder, 1861-1902 Colored American, 1837-1841 Frederick Douglass’ Paper, 1851-1855; 1859-1863 Freedom's Journal, 1827-1829 National Era, 1847-1860 North Star, 1847-1851 Provincial Freeman, 1854-1857 Freedmen's Record,1865-1874 Negro Business League Herald, 1909