Using .csv from Shared Folder(Documents)

i searched in

and

but couldnt find useful information even with keyword search "URI" and "write document"
I know that I need the URI of my document which is safed in Documents. But i wasnt able to find information how i can build the URI when i just know the path. Maybe i am totally wrong, because its my first time with URI so i didnt understand the informations given in the links above.