Try watching this tutorial on how to program the FMC or CDU (same thing)....  It significantly helped me understand how to navigate around FMC and program full flights using A/P!  After programming a couple flights into your CDU/FMC, you eventually get the hang of it and it becomes second nature on how to program your flights everytime!

This tutorial is slightly unrealistic from real life planning, but very similar to! Hope this helps!! 8-)

http://www.youtube.com/watch?v=-rZUQZe4wu8&feature=youtube_gdata_player