Someone

CREATE OR REPLACE FUNCTION TeamNamesByAge(teamDivision CHAR) RETURNS SETOF teams AS
$BODY$
DECLARE
    r teams%rowtype;
BEGIN
    FOR r IN SELECT tname FROM teams
    WHERE agid = teamDivision
    LOOP
        RETURN NEXT r; 
    END LOOP;
    RETURN;
END
$BODY$
LANGUAGE 'plpgsql' ;

SELECT tname FROM TeamNamesByAge('ag1');