Hi,
You'll need to tell us wht your system is first. CPU speed HDD & Memory size and if you have a DVD recorder.
In the meantime you'll need some software tools to help you.
DVD Decrypter will decode commercial films
http://www.dvddecrypter.org.uk/
DVD Shrink 3.2 wll fit most films onto a single layer DVD with or without extras.This is on the Doom9 website
Then Nero will burn the DVD for you, or you could use any of the freeware progams available.
This site has all you need to know on DVDs, their structure and how to use the tools I mentioned above.
http://www.doom9.org/