function doPost(e) {
var ss = SpreadsheetApp.openById('<SheetID here>');
var sh = ss.getSheetByName('Sheet1');
var params = e.parameter;
var row = parseInt(params.row);
var col = parseInt(params.col);
var val = params.value;
sh.getRange(row,col).setValue(val);
return ContentService.createTextOutput("value set");
}