Making Ginger Beer?

I want to make ginger beer to drink, it's a well known remedy. You make it by putting a teaspoon of yeast, sugar, and ginger in a jar with some water and then for 1 week you have to feed the plant in the jar with 1 teaspoon ginger and sugar. After the that you have to make it up with water and more sugar to yield a gallon. Finally you bottle it.

My question is, I want to know how much to put in over all. I was given a recipe by a friend and they have success every time, but mine was a disaster. We used to make this drink years ago and it was always good.

Regards.

By Rozjune from Nottinghamshire, UK