How to read/extract data from a web page?

Question

I am trying to build a VB.NET 2005 windows app which gets cars info from a webpage(webapplication) that has a username and password.
I was able to programmatically login to this webpage(by automatically populating the input boxes) And after I logged in, I could view the cars data in browser and I did "View Source" but the cars data (such as car model, brand, color etc..) were not viewable in the page source code. So how can I read these data with my application?
I hope my question was clear and literally need some help.
Thanks