2 of the pins you need to used PWM(Pulse with Modulation) pins. We need to connect 6 digital output pins on your Arduino. If your using two motors for a robot you need to ensure that the polarity of the motors is the same on both outputs, otherwise you need to swap them when you set the motors to forward and backward.

Wiring and controlling a DC motor is quite easy, you just need to connect each motor to A1-A2, B3-B4 or Out 1-2, Out 3-4 It depends how the L298n board configuration. If you want to build your own, see the schematic diagram below. There are many model of l298n boards in the market, see the photo below for examples. Control Logic: Standard TTL Logic Level.It can also be interfaced with simple manual switches, TTL Logic gates and relays. It is excellent for robotics applications and well fit to a microcontroller. This module has ease to connect and drive a dc motor or stepper motor allows you to easily and intently control two motor up to 2A each in both direction or one stepper motor. Additional supply input is provided so that the logic works at lower voltage. The emitters of the lower transistors of each bridge are connected together and the corresponding external terminal can be use for the connection of external sensing resistor. Two enabled inputs are provided to enable or disable the device independently of the input signals. It is a high voltage and high current full dual bridge driver designed to accept standard TTL logic level and drive inductive loads such as relays, solenoids and DC stepper motor. The l298 is an integrated monolithic circuit in a 15 lead multi-watt and power S020 package. The L298 H Bridge is base on l298 Chip manufacture by ST Semiconductor.

L298n motor driver specification