Looking for a code snippet (Plugin creation)

Hello.

I’m stepping right into the scary world of coding a simple plug-in ??
A really simple thing that i am stuck on is this:

– Have a PHP include
– The include should have a quicktag (just like Gallery). Example: [postcard] in the post section.
– Or have the plug-in create a template in the “pages” section.

What i’m trying todo, is create a simple postcard plug-in from a PHP script my friend made.

I was looking in the codex and to be honest. I did just understand i little bit of it. I’m no coder, so please don’t excecute me for asking this questions ??