How do I assign permissions to users¿?

[guarez]

Hi, I have the latest version of OpenDoc installed, running smoothly, the matter is I do not understand how to give permissions to the files.
I need to create something like this:

classroom 1
subject 1
subject 2
.
.
.
.


user1 should only have read access to the subject 1
user2 should only have read access to the subject 2
etc. ..

:?: How do I assign permissions?

I do not need users to upload files