How to stop a particular database - reg.

Dear Group!
        I have a DB server running Postgres 7.2.3.  On this server I have
multiple databases running.  I would like to stop & start a particular
DB.  How do I do this.

for example.  I have databases named test, test1, test2, etc.  Now I
would like to stop only test2 without affecting the other DB's.  Please
advice.

Thanking you,

Yours sincerely,

Shan.