OED Online through CT State Library
Good news, the OED is available through the State Library, but students do need a state card (different from a local library card).
You should download the form available here from the CT site, which you can fill in electronically, including the parent part (if under 18), and print it out for signatures. Fill in your driver license numbers where requested, or, if you don't have a license, your local library card number right above that (so yes, if you don't drive, you need to first get a library card from your local library).
Once you have your CT STATE library card, use the number to log in to the OED to start searching. The OED also offers number of free resources about how to use the database in its web site.
Think you know when different words were first documented in writing? Take the OED Timeline Challenge to see what you know?