Fiirst of all, this is not an easy process. The person has to want to be helped. Otherwise, in the terminology of Prochaska and DiClemente, the individual is in a "precontemplative" stage, not even...
The first step at a drug treatment center is usually detox. This will help your body with its withdrawls from its addiction. Next is the therapy and group counciling. It helps to be in this group...
Plan an intervention. Contact a specialist from your local rehab center to help convince this person to get help. Also, contact they're family members and ask them for help as well.