I need a jump start

I need to write a C program that will require libpq and ecpg.  I'm hoping 
someone can point me to an example.  I'm not a C programmer, so I need a crash 
course or jump start.  The original program has existed as an Informix 4GL 
program for many years.  We have lately been converting our application to 
PostgreSQL.  All the user interfaces have been written with a rather obscure 
set of tools to be run on Windows clients.  This particular program needs to 
be run with cron on the server.  Essentially, it will scan a relatively short 
list of records, compare values with records or tuples from a relatively large 
table then insert into and or update other tables.  Interestingly enough, the 
first table's name is trigger.  As most of the actions required are time 
delayed (days or weeks), triggers are not a viable option for this.

Does anyone have a suggestion for an existing program or code I can study to 
give myself a leg up on this?

Thanks, Scott