There are a couple of different methods for detoxing from drugs.
One is to do it cold turkey on your couch at home. This may or may not work for you, and in some cases it could actually be really dangerous to do this. Alcohol withdrawal in particular is very risky and could cause seizures or even death. So consider the drugs you are coming off of before going this route.
Another way is to go to a drug rehab. Out of all the drug detox methods, this one probably makes the most sense. You can get a lot of help in most rehabs and also get some direction and knowledge by attending residential treatment as well.
Yet another method is ultra rapid detox, in which you undergo a somewhat risky and expensive procedure to have the drugs flushed from your system.