Insert table mdl_files itemid filearea draft

Good evening, I'm trying to insert a file in moodle by an application outside of Moodle. Time to insert in the table there is a column mdl_files itemid that receives an integer. To be able to know how to properly insert Moodle generates this itemid when the component is user and is filearea draft so you can do this in my application also, please someone HELP me ..