You might want to take your question to a more appropriate forum. Just as there are forums and websites devoted to Sims-related topics, like MATY, there are also forums and websites devoted to CD and DVD burning, authoring, and copying topics, like
Video Help. That site has tutorials for doing a number of different tasks, like copying DVDs (which is what you want to do.) There are even alternate tutorials for different programs.
There are also additional tutorials there for special situations. For example, you are talking about copying a commercial DVD. Odds are, it's copy-protected. That means just using Nero is possibly not going to work. You may have to use an additional program to defeat the copy-protection. There was a program able to bypass some forms of copy-protection, DVD Shrink, but I'm not sure it's available any more, because even though you are legally allowed to back up DVDs or convert them into AVIs for your personal use, industry lobbyists attempt to outlaw any tool that can be used in that way.