Automated web browsing/crawling

I need to make a script that can browse through the web. It needs to fill a login prompt and click submit. It needs to fill some check boxes and/or radio buttons, submit a file and then read some info (I know which html elements to look for). All the needed info for the queries would be provided beforehand, as arguments or a config file. I have never done anything of this sort (Im in the 2nd year of my CS course). I dont know where to start.

Is there any sort of tool/framework/api that would allow me to do this (even command line utility for Windows, as I need to use an old vpn client only available for Windows)? If you could just point me in a direction it would be great!

Im confortable with Java, Python, C, C#. My most productive language being Java.

Thanks in advance