Dictionary manipulation

Hello all,

I want to ad tow dictionary together so i convert it to json,

First dictionary is string,string and second is string, list,

im trying to achieve from datatable where i loop through them and add my own elements.

{
  "startedDateTime": "2023-04-27T13:45:41.232Z", 
  "endedDateTime": "2023-04-27T13:45:41.233Z"  ,
  "message": "string", 
  "rowCount": 0, 
  "columns": [ 
    {
      "type": "string",
      "name": "string"
    }
}

Thanks in advance