Welcome to the Arduino forum,
I should start by saying that I am a n00b myself but I have managed to get a DC motor working using a motor shield
To use an Arduino to control a motor bi-directionally you are going to need a H-Bridge
. If you are just interested in moving the motor one direction then you will at least need a transistor
and some diodes
. To put it bluntly, the Arduino does not have enough power to move a motor directly through its pins, so you can't just wire the motor to the pins and expect it to turn!
The idea is that you use the Arduino to control a relay
or more commonly a transistor to connect the motor up directly to the battery (not through the Arduino).
There are quite a few tutorials online for how to do this but most use at least some discrete components (often a pre-built H-bridge chip). For an example check out: http://itp.nyu.edu/physcomp/Labs/DCMotorControl
If you are more interested in a quick and dirty "on and off" type solution check out: http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads
The best of luck with this and keep us updated with how it's going!