You need a program called virtualdub which will join the two files into one large file. Check out this tutorial.http://www.videohelp.com/virtualdubedit.htm
Then the file has to be converted to dvd format in which there are numerous programs, such as WinAvi or VSO DivxToDvd which will do the job but no menus. If you want menus then you need something like Tmpgenc or NeroExpress or a bunch of other programs to numerous to mention. There are some tutorials on this website in the Video Edit Software forum and also at www.videohelp.com

Geno888 beat me!!(type waaay too slow)