Im travelling to Germany from Canada, need advice on getting around.?

Hi, Im visiting a friend who lives in Dusseldorf, Germany in a few months. I also want to stop by at Frankfurt while Im there. I'm pretty sure there are trains that'll take me there, approximately how long is the train ride and how much are the tickets? Is there a website where I can find out the train schedule and fares?
Also, I'm also thinking of going to Prague from Frankfurt, then back to Dusseldorf from Prague, is there a train that could take me through these destinations? (my flight departs from Dusseldorf).
Thanks in advance for helping me out.

Hi, you can visit the www.bahn.de It's in english language too and it can help you with your schedules.
Regards from Frankfurt.

www.bahn.de is fine ... also check whether there are cheap flights between Prague and Duesseldorf. Duesseldorf is nice. Will u also visit Europe´s boomtown Hamburg?