When I started doing work with websites and interfacing with other websites, I originally wanted to do what you're talking about, reading the text from pages, because thats how we as people interface with computers and websites.
But that is not how computers should ever interface with other websites unless absolutely necessary.
Moodle has an API for such things like course management. Its kind of difficult to find information on, but its called Moodle Web Services if I remember quickly. I'll add a link back if I can find it.
What these will do is let you access moodle in a computer friendly way, ie. a way your computer can easily understand, instead of trying to read webpages.
Edit
Here are some resources to get you started:
https://docs.moodle.org/dev/Web_services
https://code.google.com/p/mnet-csharp/
https://delog.wordpress.com/2010/08/31/integrating-a-c-app-with-moodle-using-xml-rpc/
https://delog.wordpress.com/2010/09/08/integrating-c-app-with-moodle-2/