Converting .data files to JSON?

Hello! Where can I find information on the conservation of information in the files?
I want to store the information as follows:

Code:

{
    "SteamID": {
        "Var1": "Value",
        "Var2": "Value",
        "Var2": "Value"
    },
    "SteamID": {
        "Var1": "Value",
        "Var2": "Value",
        "Var2": "Value"
    }
    ...
}