Okay, step 1 is: forget about NPS, it's crap.
Then, search this forum for "Odin", and download it. It's a program to flash the Samsung phone without using NPS. You also need the firmware file(s), but I guess that's ok already?
You need to put your phone in "Download mode" before connecting it to Odin. You do this by powering it off, and then powering it on with [Volume Down]+[OK]+[Power]. When it shows a floppy disk icon with the word "downloading", it's ready to go.
Plug in the USB cable, and start Odin. The first "slot" or "box" in Odin should now connect to the phone. Specify the file(s) you want to install (be sure to put them in the right boxes), and start the install.
Odin will reboot the device and then wait for a new connection. At this point, the phone should be booting normally, and you can close Odin ... and be happy!
Again, search the forum for the required files and work steps, and let us know if you have problems.