Complete the form. Clearly print your email address on the form somewhere. Scan and email it to the CCT Coordinator, who will sign and submit it to the Registrar, who will email confirmation and information about your UMS number, WISER, and billing options.
If you already have a student UMS number, you can register without a form through WISER starting about 2 weeks before the semester starts. You will be sent a bill, but perhaps not until the end of the add/drop period.
Go to the first class and have the professor sign you in or see the Program Director during office hours. Then go to One Stop to complete the registration process.
Again, You will be sent a bill, but perhaps not until the end of the add/drop period.
For courses offered through University College (Continuing Education), it is possible to use the shopping cart for the semester (e.g., for Spring 12 the link is http://uc-courses.umb.edu/courses/spring/cr/gr/online/) instead of the form, but the cart asks many more questions about residency and visas that are not actually necessary for registration.
Note: "UMass Boston prerequisites and eligibility requirements" means that you have an undergraduate degree.
More details and another registration option: University website (= registering for a "non-degree course")