Replacing GFCI with USB/110 receptacle.

I have a question about electrical writing inside my house. I want to replace one of the outlets in my kitchen with a receptacle that has a USB charger and one outlet. The unit is part of a GFCI circuit, but the one I'm replacing is not the one with the test/reset buttons.
I turned the power of at the circuit breaker and opened the outlet and found it has two black and two white wires connected to it. The new dual purpose USB charger outlet has only one post on each side for connecting. I've read somewhere that the second set of wires is to pass the current on to the next outlet.
What do I need to do to set this up correctly? Can I twist the two black together and then into the outlet (same for the white)? Or do I need to make some other connections.
I'm not too knowledge about electrical writing, but pretty handy and logical about most home improvement.

 

You need to wire nut the two black wires to a pigtail (8" length of wire the same gauge and color) and do the same to the white wires and grounds. Then connect the pigtails to the new device.