This is where you can check the status of your membership, change information in your profile or change your password.
If this is your first time in this new (improved?) Membership section, you probably are totally unaware that you even have a password so just go ahead and click on Lost Your Password? and you will get a link to set one.
Note that the Renew button only appears when you are within a month of expiring. If, while renewing, you want to change the length of your subscription, just click on Change and other options will be offered.