postgresql – Importing CSV into postgres

I recently started learning psql, right now I was trying to import some csv spreadsheets into a PostgresQL database using the COPY command.

As far as I know, after installing psql, we have a new account in the system called postgres, and every time I need to use postgres I should sudo -iu to the postgres account and then do psql.

Then I was trying to copy those csv files into the data directory of postgres. I used my account but found that I cannot access the postgres data directory. What I meant by “cannot access” is that when I type cd, nothing happened.

[azure@myVM ~]$ cd /var/lib/pgsql/13/
-bash: cd: /var/lib/pgsql/13/: Permission denied
[azure@myVM ~]$ sudo cd /var/lib/pgsql/
[azure@myVM ~]$ 

I wish to know what is the “normal” way to import data? Because I guess if I am doing everything in a standard way I shouldn’t be going around modifying user access for directories.
The machine I am using is a Centos VM from Microsoft azure, and the Postgres version is 13.