The first thing you need to do is look on the Internet and find the clinic that is nearest to you, or the clinic that is in TN that you decide you wish to attend.
Get the phone number and call them up to get an induction appointment.
Here is a link to a clinic locator for you, you just need to out in your state and follow the instructions!
I'm not sure if clinics in TN have waiting lists, but I don't think so.
The clinic will give you an appointment for an induction, they will ask you for a urine sample that they will test for the presence of opiates and other drugs. They will expect the test to be positive for opiates/opioids.
They will ask you for a detailed history of your drug use, how much you use, what route do you administer it (eg, do you inject), they may ask you if you'd like them to do HIV/Hep tests for you.
Once you have seen the doctor, and they have agreed to prescribe for you, they will start you off on a dose (usually around 40mg) and they will increase that every few days until you get to a dose that stops physical withdrawal for 24 hours, and helps abate cravings to use drugs.
You will be expected to attend the clinic every day for dosing, and for other appointments with your counsellor, and possibly some group appointments, but each clinic differs on this, and they will go through it with you on induction.
Once you have got to a dose that means you are comfortable and not using, and you are giving urine samples that are drug free, you can work towards getting take-homes, so you don't have to go to the clinic as frequently.
If you are prescribed benzodiazepines (such as Valium, Xanax), some clinics will not let you have take-homes, and some even will not let patients be on benzo's full stop. If you're not on them though, this is obviously not an issue for you.
The clinic will expect you not to drink excessively, some clinics will not let you smoke pot, and they will expect you to abstain from using all illicit and un-prescribed drugs
There is quite a lot to methadone treatment and the clinic system, but that it a little bit of it in a nutshell!