Measure the amount of liquid in ml. Then measure the same amount in grams in sugar. So for example 100 ml liquid means 100 grams of sugar.
Degrease a bowl (for example with some lemon juice and a clean kitchen towel).
Time to whisk!
Add the liquid to the bowl and add 1/2 teaspoon of vinegar or citrus juice.
Whisk the aquafaba until white and fluffy. It is ready once the whisked up aquafaba is sticking to the bowl. This means that you can hold the bowl upside down (without the mixture moving).
Then add the sugar, spoon by spoon, while whisking. When the meringue is glossy and all sugar is incorporated, it is ready.
You can use this meringue as regular meringue in any recipe :)