How to load a file?

Watch here:

Why is the file picker not displaying my files?

Please make sure to select 'Show internal storage' from the toolbar menu.
Watch here:

What are the supported file types?

The file loading is restricted to certain MIME types that might represent a valid JSON or XML.
Loading files with other MIME types, requires user confirmation.
The current supported MIME types are:

*/*
attachment/json
application/*
application/json
application/octet-stream
application/txt
application/xml
text/x-json
text/csv
text/comma-separated-values
text/html
text/plain
text/xml
multipart/alternative
multipart/mixed