Interrupts using Keyboard

I was wondering how one could go about using _getch() to generate interrupts based on the keys pressed.
I don’t know how to create an ISR for this purpose that would prioritize a task to perform over the others.

I think you asking a question that is more hardware-related then FreeRTOS. FreeRTOS’s kernel provides no direct I/O support (you can find some examples in the demo’s though). A keyboard would likely be connected through a serial port or perhaps a USB port, and you would need to implement the logic in the ISR for that.

Generally, you don’t change the priority of tasks in an ISR, but make the data ready so a task that might have been asleep wakes up.