https://eweb1.laccd.edu/WebStudent/signon.asp

above is Student Information System,

login with your student ID and mmdd

then go to "main" and add or change your email address

when you email a request to add a class to ProfJ, the email request must be the same as the one your have at your SIS, for the school to authenticate and validate you are the true person registering by way of electronic email instead of the usual paper "add" signed by the student. Admissions allow this special way for online students, but the emails must match between the email sent to add the request and the email registered at the College SIS 

good luck.