You have to be in college(not High School, I already asked a rep) if you want the Student membership, and in a major related to Electronics or Electricity. All you do is fill out some information on the website, give a Credit card #, and they send you the card in the mail.
If the IEEE is anything like the IEE/IET then you should be able to join by filling out an on-line application form. If you are going for professional registration with the said body, then you will need to send them copied of the appropriate paperwork to satisfy their registration criteria.