Primary means written at or near the time of the historical event.
Secondary means written many years later, probably by a scholar researching the historical event.
In most databases an asterisk lets you include alternate endings. For instance, enlist* will search for the words enlist, enlistment, enlisted, etc. This can be very useful in retrieving more results.
When you find a relevant title in the library catalog/search system, look for these Subject Headings (or "Subjects") to find additional sources on that topic.