Write in txt file on sd card intelligent nextion

Hi!
How to write in file placed in sd card for intelligent nextion?

Place a file component on the page and use its open and write methods. Understand that the Nextion has no full fledged file system, it can neither create files nor change a file size (append) - you have to create the file and to allocate its size before you put the SD card into the Nextion. Then, you can write until the previously allocated file size is full.