Basic Trigger Question

I've used triggers before in another DB  where the total functionality
was included in the CREATE TRIGGER statement, totally written in SQL. I
understand that postgresql can't do that (correct?).

I want to delete a row in table 2 when I update table 1, with something
along the lines of :
CREATE TRIGGER mytrigger AFTER UPDATE ON table1
    FOR EACH ROW
           DELETE FROM table2
    WHERE table1.id = table2.id

Afterwards I will re-insert any necessary info into table 2.


Can anyone help me with this?

TIA

ps If I need to use a function to do this, pls show me how to do the
same with a function.

--
Ron St.