Start at the library home page. You can't miss the search box. The default is to find "Information," but you have the alternative to find "Help." Searching Help is for when you need information about the library -- our policies and procedures, information about our services, how to use our resources, and the like. But the Information Search searches the vast ocean of data available in the discovery service. Depending on our terms, you might get tens or even hundreds of thousands of matches, but there are many options from there to help narrow your results.
You do not have to log in to search EDS. If you are on campus, much of the full-text content will be available directly without logging in either, while if you are off-campus, you will likely be prompted to authenticate with Google Apps for "proxy access" that allows you to enter a restricted resource as if you were on campus.
You do not need to create an EDS account, but there are advantages to doing so. You will be able to download e-books to your tablet or laptop and read them offline for up to two weeks. You can also save searches, add books and articles to folders that will be available the next time you log on, and create email alerts when there is new content that matches your interests.