First thing is adding the file and double-clicking it. You'll open the text editor.
JSON are very specific about how you write them. There can never be commas in the last statement in a section, and every variable must be inside double quotes, as you can see below:
Then you can load the file into an object. You can then read and write to the object, like below.
The resulting text from this experiment would be like below:
These are all basic tips for you to get started, but feel free to continue this thread if you have any more doubts on the subject.
Hope it helps.