Step 1: Materials Needed

Tamiya Track and Wheel Set Assembly ($7.95 at Pololu)
Tamiya 70168 Double Gearbox Kit ($9.25 at Pololu)
L298N Dual H Bridge ($3.65 at Amazon and might be much lower at ebay)
4AA Battery Holder (used from broken electronics)
200mm Female and Male Jumper Cables ($2.60 at Amazon)
Universal Tamiya plate ($7.77 at Amazon)
Arduino Uno or its clone

Note: Universal Tamiya Plate is optional. That is you can use wood in place of it. But, for convince I've used the plate.

Step 2: Procedure

Assemble the gear motor as described in the manual. For this project I've used 114.7:1 gear ratio
Mount the double gear motor onto the Tamiya plate
Connect the 6V battery holder (+) to the L298N +12V port and (-) to the GND using jumper cables
Connect the arduino GND to the L298N GND
Finally, connect the motors to the L298N two side output ports
Follow my drawing for circuitry for further clarity
Connect the pins of L298N to Arduino as the following:

Right side

Pin1 --------------------------------- 3 of Arduino (PMW pin)

Pin 2 --------------------------------- 6

Pin 3 --------------------------------- 4

Pin 4 --------------------------------- 13

Pin 5 --------------------------------- 12

Pin 6----------------------------------- 9 (PMW pin)

Note: Don't worry about the polarity of the motor connection because we can change it through the code

Step 3: Code

First of all, download the Arduino Software from their website. Then copy and paste the following code:

void setup(){
 Serial.begin(9600);
 //right motor
 pinMode(3,OUTPUT);
 pinMode(6,OUTPUT);
 pinMode(4,OUTPUT);//pwm
 //left motor
 pinMode(13,OUTPUT);
 pinMode(12,OUTPUT);
 pinMode(9,OUTPUT);//pwm
 
}
void loop()
{
  int Racerspeed=80;
  int ReverseSpeed=60;
  //forward
 digitalWrite(6,HIGH);
 delay(100);
 digitalWrite(4,LOW);
 analogWrite(3,Racerspeed);//right motor</p><p> digitalWrite(13,HIGH);
 delay(100);
 digitalWrite(12,LOW);
 analogWrite(9,Racerspeed);// left motor 
 
 delay(4000);
 //reverse
 
 digitalWrite(6,LOW);
 delay(100);
 digitalWrite(4,HIGH);
 analogWrite(3,ReverseSpeed);</p><p> digitalWrite(13,LOW);
 delay(100);
 digitalWrite(12,HIGH);
 analogWrite(9,ReverseSpeed);// left motor</p><p> delay(5000);</p><p> //stop
 digitalWrite(6,LOW);
 delay(100);
 digitalWrite(4,LOW);
 analogWrite(3,0);// right motor</p><p> digitalWrite(13,LOW);
 delay(100);
 digitalWrite(12,LOW);
 analogWrite(9,0);// left motor</p><p> delay(5000);
  
 //turnleft
 digitalWrite(13,LOW); //changed this (7/12/2015)
 delay(100);
 digitalWrite(12,HIGH);
 analogWrite(9,30);// left motor</p><p> digitalWrite(6,HIGH);
 delay(100);
 digitalWrite(4,LOW);
 analogWrite(3,120);//right motor</p><p>  delay(1000);
 
}