how to USB on a pic 18f (Pic18f47j53 )

how to use USB on a pic 18f (Pic18f47j53 ) ?

Hello everybody I'm here because i want to program a pic 18f47j53 in USB mode. Unfortunatly i dont understand a damn thing about how the HID works :s if someone can explain me pliz ?! i have see a lot of tuto on the net but no one can really explain until the beginning how to make work an USB connexion.
I read a lot of tuto and i dont get how the PC can communicate with the PIC , does it pass by an other program already install on the PC ?
In addition for example i just want to light a LED on my PIC when i give an order on my PC. ( i have already try to use the example give by microchip but i start the demo and nothing happens ... that's why i was thinking about a programm on the PC different from MPLAB but who works with him )

Thx for your attention See you !!