where do I sign for new service?

Best is you should come to the office. But I think in some cases you can do it online/ over the phone.

TAG offers a lot of filter Solutions every person the best for his needs. so there's no one place to sign up because you should first discussed with them which filter will work the best for you and then you can sign up online. so either call in or go into the office and figure out which filter will work the best for you then they will tell you where to sign up.