If you do not understand the difference between being an AFSCME Local 328 member vs. being a fair-share payer, you should review the attached tip sheet, "Dues vs. Fair Share." The tip sheet lists all the benefits you get by being a member, including the right to vote on a new contract.
To check whether OHSU has you listed as a member or as a fair-share payer, look at the After Tax Deductions section of your OHSU earnings statement (see #34 in the "Understanding Your Earnings Statement" PDF attached below.) You should see either AFSCME Dues or AFSCME Fair Share. If you find out you are a fair-share payer and want to sign up to become a member, just click on the Become a Member link on our website and follow the instructions.