I want to be fat,because I am very thin,that is problem everywhere. So please specifically tell what should I do now?

When you say you want to be fat do you mean that you want to put on a bit of healthy weight, or are you asking how to become obese?

Obesity isn't healthy, so I doubt that anyone on this site will advise you to do something that isn't good for your health.

But, if you're extremely thin and want to put on a bit of weight to be more healthy, then we can help.

If you can first tell us which scenario is correct, then we can answer accordingly.

I want to be healthy in one month but how it should be possible?

I want to be healthy in one month but how it should be possible?

Gaining healthy weight is actually harder than just getting fat.

First I'd recommend a complete physical from your doctor. Your thyroid may be off, which may be why you have issues with gaining weight/being too thin.

Your doctor can also recommend a diet that will boost your weight, while still being healthy.

It's really not possible to gain healthy weight in a month. This is going to take time, just like losing weight takes time. First see your doctor, then go from there. Your doctor may even recommend that you see a nutritionist.