Get a 2 litre bottle-An empty plastic one that has held cider, beer or pop. One of those big fizzy drink bottles.
Wash it out or just throw away the stuff inside.
Add 12 oz Sugar
1 oz dried Ginger
Juice of a Lemon-Or a good squeeze of jif or bottled lemon juice
1/2 teaspoon of beer yeast- Munton's Standard will be fine.
Put it all in the pop bottle and fill up with cold water.
Screw the lid on and leave in a warm place for a few days,
The bottle will go hard then you'll know its fizzy- It may take a week in cold weather-Pop it in the fridge and drink when cold.
Adjust the recipe to suit yourself, too hot use less ginger, too sweet less sugar Etc.
Make it a few times and devise your own recipe!
If it goes flat put it back in the warm...
BE CAREFUL BECAUSE THE TOPS CAN FLY OFF THE BOTTLE WHEN YOU OPEN IT!