This is a general question on how plugins work together. I'm having difficulty grasping some concepts of WP.
In wordpress when I'm working with multiple plugins how are they integrated to work together so that it's seamless. For example I'm using 2 plugins: One is a Classified Ad plugin and the other is a Private Messaging plugin. Currently the Classified plugin only allows users to communicate by sending emails kinda like craigslist, however I want them to communicate internally on my site. So in the Classified plugin page, when I hit "reply to user" it shows me the Classified Ad's reply page. However at that point I want users to use the Private Messaging plugin so they can communicate on my site internally.
How do I direct the user to the Private Messaging plugin page AND have the Private Messaging plugin understand who both parties are? In other words, would something like this require more complicated programming skills with the use of filters and hooks...etc? I guess that's my real question.
Sorry for babbling on here, I'm just really reaching my limites of frustration with wordpress and have struggled to fully grasp the concept of WP.