Finely chop your ginger and add it to 1 litre of water in your saucepan, bring to the boil and then leave to simmer for 30 minutes, making sure you put the lid on the pan at all times.
once the ginger has been simmering for 30 minutes sieve the contents of your ginger liquid into the new pan.
Add your apple juice to your ginger infused water and slowly bring to the boil.
once the liquid has been boiling for a minute or two add the sugar, stirring it slowly until all of the sugar has dissolved.
As soon as all the sugar has dissolved, turn off the heat and make up the liquid to 4 litres with boiling water.
Put the lid on the saucepan and leave it to cool until room temperature. (20-25c or 60-77f)
Once cool enough to handle, using your funnel add the liquid to your demijohn.
Add the yeast and place under airlock, making sure the temperature is between 20-25c (60-77f).
Now place it in a warm dark place, so it can happily start fermenting to it's hearts content