The short answer is, “You can’t.”
Addicts of all kinds, including alcoholics, have to help themselves. They do not seek relief until they are so miserable that they see no alternative. Therefore “helping” one is usually the worst possible thing that a friend or loved one can do. Making sure they have enough to eat, helping out with the rent, giving them a place to stay when they blow the rent on liquor or drugs, giving them rides to the liquor store, bringing them booze so that they don’t have to go out themselves, bailing them out of jail, allowing them to get away with stealing you blind — all of those things that seem like the sort of thing friends and loved ones do, in reality allow the person to continue in their alcoholism/addiction without truly facing the consequences. This is called enabling.
Those who truly wish to help a person with a problem will assure them that they are loved, but that they cannot expect assistance in anything but getting treatment and sobering up. Be aware that they will then pull out all the stops and try to bully or guilt you into doing things their way. They will make all sorts of promises. Don’t believe them. They are terrified of quitting — for excellent reasons — and they will do or say whatever it takes to continue drinking or using. They do not understand that they have a choice.
Well-meaning friends and relatives who try to take the pain and unhappiness out of the addiction are keeping the person from finding a reason to make changes, and until that happens, recovery IS NOT POSSIBLE! Enablers are helping their loved ones to kill themselves.
If you are a family member or employer, you can consult with an addiction professional about arranging for an intervention. Do not attempt to intervene on your own; it almost certainly will not work. Intervention specialists know all the tricks, and are able to set up immediate referrals to detox, treatment and so forth. You don’t have access to those resources, and an intervention that is only done halfway is likely to waste what may be your last effective shot.
All you can do to really help is drive them to detox when they decide they want to go there, and withhold all other assistance. There will be plenty you can do after they have been sober for a while and have learned to function on their own, but there is nothing you can do until they make up their mind to take that first step.
For their sake, don’t stand in their way by “helping”.