Databases, for the purpose of writing a paper, are a collection of organized journal articles, trade articles and sometimes popular articles that are aggregated by a subject. They are searchable by using an organized strategy-keywords, controlled vocabulary, and Boolean search terms, truncation and a whole host of other techniques. I only want you to be concerned with search terms and how you enter them into the query box. Remember, in the case of searching what you put in largely determines what you get out-it is just a computer.
Keywords look for any word or word combination whereas, a subject search uses the Library of Congress headings to organize/retrieve the information. You should be okay at this level to use keywords. The trick is in how you combine them to search.Most databases use the Boolean methodology to effectively search.
Here is a link to a very quick video on Boolean searching:
Below are a few databases to get you started, but try to think of selecting your database based on your question. Think of it as the main road that you have to travel.
Primary resources or sources, constitute information that is recorded directly from an event. There are no interpretations to the information. The information is presented regardless of time or observer. Primary resources are concerned with just the facts, however, it may vary for say, a copy of the Constitution, where the copy would be considered a primary resource.
Secondary resources are documents or information that has been interpreted the through the lens of another. This means the information is now subject to interpretation by analysis or criticism.