For most papers you write, I recommend that you search individual databases. Choose a database based on the subject area of your paper. You can choose databases by subject from the libray's home page. On the left side of the page, choose "Find Articles by Subject" and once you've done that, choose the subject area corresponding to your research needs. Then choose a database from the list.
You also have the option of using the "OneSearch" tool on the library's homepage. This searches all the library's databases, and the online catalog (for books, DVDs, etc) at once. This is a neat tool, but often you get too many results, over a wide variety of disciplines, which can be overwhelming.
If you choose to use this the OneSearch tool, be sure to watch this brief tutorial first, so you understand how to use it correctly: