You have not said what type of DVD you are trying to copy. If its a commercial film then its probably protected to stop casual copying, thats not to say you cant copy it, but you would need a DVD ripper and also a program to bypass the protection, from memory there is a utility called CSS.
You would also not be able to fit a DVD on to a CD as the storage capacities are totally different. You would need a further program to encode the MPEG2 stream used on a DVD to a different format such as DIVX which will compress the data down to fit in the smaller CD's capacity.
Lastly, unless you are running windows XP which has some rudimentary DVD copying software built in, you will need a program to write the CD.
Of course, if it is not a commercial film then you can ignore most of the above and cut straight to the encoding process after ripping the DVD.
As you can see it is a lot of hassle and I heartily recommend that its just easier to buy the DVD.