Hi, i'm a bit new to pmdg-777 200 and can't find a solution to my problem which is: 

 

     http://prntscr.com/3ngrbj

 

Can you help me to fix the problem, tnx in advance

These two things actually have nothing to do with each other.

For the red cross, you need to contact PMDG (support.precisionmanuals.com)

For the LANDING ALTITUDE, follow the tutorial first. This "error" (it's not an error) will go away if you select a destination in the CDU.

I actually think one gets the "landing aptitude" error shortly after the "landing altitude" error. One from the PFD and one from the chief pilot!