Why are there only 2 white wires in my celling outlet box for me to install celling fan and light?
Stop.   Your box is not rated for a fan.

You cannot simply put a fan on that junction box. The vibration will tear it out of the ceiling. 

You may be able to resolve it by mounting a purely physical fan mount right next to it, which is fan rated, and using this junction box only to bring electrical (not carry its weight). 

Once that's resolved...

Light + fan on one switch

You don't have enough wires to control fan and light separately.  You must join the black and blue wires to each other, and connect them to a point to be determined. 

Take ground to the screw in the back left of the junction box.  

You have two cables coming into the box with a black and white in each.  One of the cables is the supply power, and black is hot and white is neutral. The other cable is a switch loop, and it is wired with black as always-hot and white as switched-hot.

Pause here and identify which cable is which.  Code requires the switch loop use the white wire for always-hot, it must be marked with tape or paint (on both ends) to designate that it is not a neutral.  

Get a non-contact voltage tester and unhook all 4 wires (non-grounds) and turn the power on. One of the 4 wires will be hot, it will be a black, and that cable is supply.  The other cable is switch loop.  Mark the white, and join it to the supply black and push it into the back of the box.   Now the remaining wires will be white and black, and those colors will be valid.  

From there it is straightforward; lamp black+blue to black, and lamp white to white. 

All singing, all dancing on the wires you have

For this you need smart switch tech, and a module that sits up in the fan rose.  The module connects separately to fan blue and black, power, switch loop, etc.  Then either a companion (matching) smart switch is installed in the switch box, or the switch is wired to control light only and a remote is used for the fan.  The instructions will say how to wire it.