The setCellValue operation allows you to set the value of a specific cell through the SheetSearch API. This will likely be followed by other operations, most commonly saveSheetData.
// Initialize SheetSearch
var sheet = new x_vivid_sheets.SheetSearch('a6b4ff401bac8af00df574cf034bcb3d');
// Set the value of the specified cell
sheet.setCellValue('B4', 1225);
// Save the sheet's data
sheet.saveSheetData();