Passing arguments to a function called by a trigger

I have an INSERT AFTER trigger that runs on inserts into a specific
table. I'm not sure if the function automatically gets all the
information that was inserted into the table or whether you have to
manually pass it in?

If you do have to manually pass it in can someone point me to some
examples showing the correct syntax to use? I've read through the
PostgreSQL manual on C functions but most of the trigger examples don't
take any arguments unfortunately.

Also while I am on the subject can anyone recommend a good book on
stored procedure programming with PostgreSQL please? I use plpython2u
and C for my stored procedures if that makes any difference.

Thanks.