code: public boolean upload(WebLocator el, String filePath) {
          return executor.browse(el) && executor.upload(filePath);
      }
docs: Upload file with AutoIT.
  Use only this: button.upload(this, "C:\\text.txt");
  
  @param el the item that you click to open upload window
  @param filePath e.g. "C:\\text.txt"
  @return true | false