Then go to Training: Research Involving Human Subjects page by using the menu titled
Education and Training > Human Subjects Training
Read through the page, and then under the section, How to Register and Complete CITI Training?
find and click the link labeled,
detailed instructions
Read through this page, and then go to the CITI training page as an MIT affiliate by clicking the link in the line that says
For MIT Faculty, staff, or students: Please log into the CITI site via the MIT portal
This page let you access the CITI training+test site as a member of MIT (so they can identify you and certify you), thus
you will need the MIT certificate on your browser when you access the page.
As the page says, there are 3 types of test (training courses), and you most likely would like to take the one for
Social & Behavioral Research Investigator
Other courses are for people working on clinical experiments, etc.