Log into the website and go to the lists page. Click on the LISTNAME heading and select "unsubscribe". Go to the bottom of the page and pres "Submit".
Make sure you have registered on this website and logged in.
Then go to the lists page and find the lists you wish to subscribe to. Click on LISTNAME and then choose one of "Subscribe for digest (receive emails in a bundle)" or "Subscribe for all Mail (normal delivery)". You may optionally choose a password too.
Once you have subscribed to LISTNAME and any other lists you wish to be on, go to the bottom of the page and press "Submit".