Get content from changing website

Hi all

I am busy writing an application that will retrieve stock graphs from the internet. Due to the changing nature of stocks, I can't use the same graph today as what I used a week back.

The thing is that the website where I get the graphs from I need to sign in before I can navigate to the graphs. Is there a way to do this? I wish I could present you with some code that I have tried, but I have absolutely no idea how to do/write this code.

Any help will do (even if it is directing me to a reliable programming source).

Thanks in advance