LOL. OK, well you are kind of tackling a project that requires a LITTLE bit of background, but I have faith you can pull it off.
Start off by Googling "555 PWM" or "555 motor control"
A 555 timer is an ASTABLE OSCILLATOR in a PWM (pulse width modulation) circuit.
PWM means what it says, a chip creates a pulse signal, in this case a "square wave". It is like turning a light switch ON and OFF. Think of a jack-o-lantern smiley face, a row of teeth with a missing tooth inbetween each existing tooth (kind of like this: _-_-_-_-)
The "width" of the pulse, or the DURATION is controlled by the circuit, as is the FREQUENCY of the pulse. Combining these controls allows a pulse of a specific, chosen duration (2-3 seconds in your case) and a on/off frequency that permits spacing of your choosing between pulses (30-40 seconds between pulses in your case)
This chip is not powerful enough to directly drive your motor, so it must be interfaced to the motor via a relay or drive transistor. A circuit that frequently turns on and off is best suited for a transistor instead of a mechanical relay, and in your case I suggest a POWER MOSFET (Metal oxide field effect transistor). These are most commonly used in digital circuits and are very suitable for DC motors.
So, the output of the 555 timer chip turns the transistor on and off, which in turn applies power to the motor. For a MOSFET drive circuit, it is advisable to use a CMOS (complimentary metal oxide) chip because the output impedance is well suited for driving a MOSFET.
The frequency of the timer is set by the trigger capacitor. A large value capacitor in microFarads will slow down the frequency at which the timer creates a square wave. The re will be a variable resistor to control the width of the pulse.
To build this, and understand it, you need to study how capacitors effect frequency in a timer circuit. You should also learn about transistors and oscillators. Knowledge of Ohm's law is important for determining impedance characteristics of the circuit.
Google has a TON of information, but start out Googling the above search terms and come back with questions!