All of the videos involving the WIFI board ESP8266 only talk about turning on an off lights.
How easy would it be to alter the code to control motors?
How different is the code going to be when it is altered?
Which type of motor?
How different is the code going to be when it is altered?
Silly question. Obviously that is going to depend on what code you alter, and how you alter it.
Instead of lights you can use motor 
As was asked earlier it all depends on what type of motor.
If you have a simple dc motor (2 wires) then its likely that you will need no changes to the code. However you will need to connect your motor to the ESP8266 differently as the motor will draw much more power and likely destroy your board without some kind of interface circuitry (eg transistor, mosfet or relay).
If you have a stepper motor (which has 4 or more wires) then your code will need to change in order to make it work- there are pre-written software libraries that do most of the hard work for you so the changes will not be too great.