Using DC motors

[Guy_E]

Hi,
I have another question, but this time rather more complicated.

I have 2 DC motors which I want to connect to the VEX controller. Because they are DC I can't connect them to the PWM port.
My Electronics teacher has suggested me to build 2 small electric circuits using L293 chips that control motors, connect each chip to an amplifier and connect all that to a digital output.

If I do all that, I will we able to simulate a PWM signal, using the digital outputs and a timer.

My problem is that I don't know how to write the code for the PWM control in a way that it will be running simultaneously with the general code of the program.

Can someone help me?

I hope I've made myself clear,

Guy