Good news! Developing search terms and strategies for literature topics is easier than for most subjects.
Notice the drop down menu next to the search box. Depending on the database, you have several options. You can search for Title, Author, Poem, or Short Short Story in EBSCO's Poetry and Short Story Reference Center database and in Literary Reference Center you can search by Keyword, Title, and Author.
A keyword search is what you are used to. Simply title a "key" word related to the information you are hoping to find, such as: critical theory or symbolism. You can combine keywords to get more specific: symbolism AND poetry.
Just like a Google search scroll down the list of articles. In EBSCO databases make sure the box Full Text in the left column of the page is checked so you get only completed articles and not just summaries. Play with the other filters in the left column if you get too many results and you want to narrow the list down.
In the Gale database you have to click Advanced Search tool to get the drop down menus. Gale also has a very cool and colorful Topic Finder tool - a visual way of searching. You can find it beneath the search box on the main page. Play with it!