hi very easy, use craxtion and make sure you have the 2 isos (or game folders) you want to put on the disc choose multigame menu fit as many on as you like til theres no more room create the iso, burn with (my favorite burning tool for xbox games) stomp recordnow max you can use a number of other burning progs too. Ive had success with disc juggler, nero, ashampoo etc also make sure your xbox is able to read your media type/brand good luck
If you use Nero to do it, you won't get an Xbox iso file, just a normal one. You have to use Quix or Craxtion to make an Xbox iso file for it to work properly.