How can I manpulate how the JSON file displays its data?

So far I can read a excel spreadsheet and convert it to JSON but I’m struggling to manipulate what data i want from the spreadsheet and how I want it displayed.

this is how I read the sheet and add it to a list

foreach (Row row in rows) 
            {
                Dictionary<string, object> rowValues = new Dictionary<string, object>();
                int columnNumer = 1;

                List<InterfaceRecord> interfaceRecords = new List<InterfaceRecord>();   


                foreach (Cell cell in row.Elements<Cell>())
                {
                  
                    string columnName = GetColumnName(columnNumer); 
                    string cellValue = GetCellValue(cell, spreadsheetDocument);


                    rowValues[columnName] = cellValue;

                    InterfaceRecord record = new InterfaceRecord();
                    decimal value = -1;
                    decimal.TryParse(GetCellValue(cell, spreadsheetDocument), out value);
                    record.Value = value;
                    record.SampleNumber = "";

                    interfaceRecords.Add(record);

                    columnNumer++;
                }
                data.Add(rowValues);
            }

Here is how the JSON is converted

            //convert to JSON
            string json = JsonConvert.SerializeObject(data, Formatting.Indented);
            string jsonPath = properties.Path;
            string randomFileName = DateTime.Today.Ticks.ToString();
            File.WriteAllText($"{jsonPath}\RandomFilen.json", json);

Maps a numeric column index to its corresponding letter-based column name used in Excel.

public static string GetColumnName(int columnNumber)
        {
            int dividend = columnNumber;
            string columnName = string.Empty;
            int modulo;

            while (dividend > 0)
            {
                modulo = (dividend - 1) % 26;
                columnName = Convert.ToChar(65 + modulo).ToString() + columnName;
                dividend = (int)((dividend - modulo) / 26);
            }

            return columnName;
        }

Here is the interface

class InterfaceRecord
    {
        public string? SampleNumber { get; set; }
        public decimal Value { get; set; }
        public DateTime CreatedAt { get; set; }
        public long ClientID { get; set; }
        public string? MachineName { get; set; }
    }

Here is a sample of how the JSON file originally looked

"A": "Sample Name",//this is the Sample Number
    "B": "Description",
    "C": "Saved or unsaved State",
    "D": "Spectrum quality check summary",
    "E": "SiO2"//This is the value

This is how I want it displayed

"Sample Number": "123-ABC",
    "Value": 0.1234,
    "CreatedAt",
    "Machine Name": "Analyzer A",//Not in spreadsheet, just how I want to categorize
    "ClientID":  123