You have to make a plant first. 

1 Glass Jar - no lid

Put 1 Cup of WARM WATER in.  Then add 1 Teaspoon of DRIED yeast, 1 heaped teaspoon of Ginger Powder and 2 level Teaspoons of Sugar.  Place a piece of Muslin (i use a piece of a Chux dishcloth (a new clean one, please) and put a rubber band to hold it on.

Feed every day for 7 days and on the 8th day, strain the plant through muslin, saving the residue to start the plant going for the next week.  The first time I do this I put all the residue back in the bottle with the water, ginger and sugar.  No more yeast required now.

Ingredients required

1 kg sugar

1/2 cup lemon juice - strained

Method

In a big pot put  4 cups of boiling water,1 kg sugar (white) and stir until sugar dissolves then add 1/2 cup strained lemon juice then another 20 cups water plus the water/ginger that you have strained.

Bottle in clean plastic or glass bottles (I use plastic drink bottles) seal tightly and leave for at least a week.

The third time I replace the residue from the straining of the plant into the jar, ready to feed again, I halve the residue otherwise the plant becomes too big.

Another tip is that I find the first lot out of the plant isn't as fizzy, so I don't make the actual beer until the 2nd lot of the plant is ready.

But do be wary when you open the top, because depending on the weather, it can be very fizzy, and very sticky if you get it all over you.  So don't say you haven't been warned. So undo the top slowly to let some of the fizz out.

Also don't keep them in a cupboard with anything else.  I use plastic because they can explode and glass makes a mess, so I'm told, but it has never happened to me yet.  But if it does hubby has to clean the mess up, because I make it for him.  So he's been warned.

In the cold weather it will take longer to fizz.