to download from US market, you will need to change your region to US.
to do that, go to Setting>Language+Region>Country and select United States.
it will ask for a reboot. just let it reboot and you can download from US market.
my recommendation is to download appswitch from US market if you switching from another os.
if you have an apps that u like a lot in iOS or Android, AppSwitch will help you find an apps that is similar to it in window market.

Guys, why my phone only show "Local Network Operator" instead of "My Celcom"? Have tried to restart the phone but still the same

In Setting > Mobile Network, under Active network its only show "50219"
Network selection i put in Auto. When manually search, able to see in the list Celcom, Maxis, Digi.