Uload file on custom module via rest api 4.1

Hi,
I’ve created a custom module of document type.
I need to upload a file in cusrom module using web service (standard REST api 4.1) but I can’t find the right parameter to use.
I can create the record, but the file was not uploaded.

Here the JSON parameter I’m using:

{
“session”:"{{id_session}}",
“module_name”:“MyCustomModuleName”,
“name_value_list”:{
“id”:"",
“document_name”:“Sample Image”,
“filename”:“sample_image.jpg”,
“inj_parcheggio_inj_documenti_in_parcheggio_1inj_parcheggio_ida”:"{{id_incarico}}",
“file_mime_type”:"‘image/png’",
“file_ext”:“png”,
“file”:“encode64(…\MyFile.png)”
}
}

Is it possible upload a file in custom module?
Which the right name/parameter to use to do that?

Thanks

Matteo