yet another thread where no details are given...
if you want a correct answer regarding your specific scenario you really need to provide model numbers for the equipment involved as well as describing what you have hooked up, otherwise we can only offer generic advise which may not be of help.
now i am assuming that you have one of those cheap home theater in a box (htib) type setups with an integrated dvd player. of course dvd will always work with such systems as its built in. however, as far as aux sources of audio are concerned it can be very hit and miss. some support 2.0 input, some support 5.1 it really depends on the model.
generally these are your options for connecting to get audio between the two... depending on what your...