To renew your ICP membrship, LOG ON to your account - your logon is typically your email and a password. If you have never logged on to the membership portal or forgot your password you can request it on the logon page.
This is what the login page looks like. Enter your email and password. If you do not know your password, click "forgot password". 
Here is the logon page - click in the upper right where it says "Log in"