Sorry, real newbie question about connecting to a database

I am developinng an appliction usig Postgresql 11, installed on a UBUTU
18.14 machine.

I ahve vreated a new database to do some testing on restricting access of
specific users/roles to certain data. I have done the following:

REVOKE ALL ON DATABASE pertest FROM employee;
GRANT CONNECT ON DATABASE pertest TO employee;

and I have verifed tht the user employee does exst, I have also doen a few
more GRABTs to allow specific acces. But I cannot conect, or swith to user
employee:

stan@smokey:/etc/postgresql/11/main$ psql -U employee
psql: FATAL:  Peer authentication failed for user "employee"

stan=> \l
List of databases
 Name    |  Owner   | Encoding | Collate | Ctype  |   Access privileges   
--------+----------+----------+---------+---------+-----------------------
pertest   | stan     | UTF8     | C.UTF-8
                                | C.UTF-8 | =Tc/stan             +
                    |         | stan=CTc/stan
                                             
                             employee=CTc/stan

Sorrry cut and paste mangled that.

What am I failing to do here?


-- 
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
                        -- Benjamin Franklin