There are only two* ways of doing this:
1) If your campus has an officially chartered active chapter, introduce yourself to someone in the chapter and make an effort to meet the Brothers. If it becomes apparent that a mutual fit exists between the chapter and yourself, you'll receive a bid to join. You will then complete a pledge period designed to teach you the history, traditions, and organizational structure of the Fraternity. Upon completion of your pledge period and any other applicable requirements, you will then be initiated according to the Ritual. For more information, contact your Office of Student Life or similar campus official in charge of fraternities and sororities and/or speak with any SAE on your campus.
2) If your campus does not have an officially chartered active chapter, you may petition the Fraternity Service Center (IHQ) to start a new chapter or restart a previously existing chapter on your campus, as applicable. For more information, refer to the information provided
here.
* - The Fraternity Laws of Sigma Alpha Epsilon do provide for the possibility of special, non-student initiations, but these are rare and only approved in very special circumstances. This is generally only possible through an existing chapter of SAE.