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