Look at the datasheet for the L298 motor driver.
1) It has a 5v supply (VSS) for its logic and up to 46V supply (VS) for the motor.
2) It has an output voltage loss of 3.2V max with a 1A load and it increases to a loss of 4.9V max with a 2A load.
So you will need much more than 9V input for 9V output.
According to your diagram and the data sheet for L298N, all you have to do is connect 9v to VS, 5v to Vss. Connect the motor as in your diagram. Connect pin 10 and 12 to the port pins of your PIC. And write codes to the port to switch port to 1 or 0 according to the truth table in your diagram. And that's it.
Now you are little more clear to us. you may also take 12V from the same PC if available , use 7809 and thus derive (V DC for your needs. put a suitable heatsink for the 7809 regulator.
Hope this serves your purpose.
Otherwise you can derive 9V from %V by using step up converter mode of MC34063 but i am not sure it may deliver the needed load current???