1. load the flash tool
2. choose which file you wanna flash
3. turn off the phone (you should copy the ROM.zip and gapps.zip to your phone before since you cant do it except using card reader and dont forget to turn on USB debugging in the settings)
4. when the flashtool ask for the phone, DONT EVER TURN IT ON, just HOLD BACK BUTTON WHILE PLUGGING THE USB CABLE TO YOUR PHONE.
5.wait, then when flash tool ASK YOU TO REMOVE YOUR PHONE remove from USB and flash the ROM using CWM by pushing back button after the kernel logo
disclaimer : i will not taking the responsibility if you bricked your phone. good luck
for video, you can see it on youtube