Without actually going to school you can read a book. Here is one.http://www.amazon.com/Automotive-Steering-Suspension-Alignment-Edition/dp/0132747766
A wheel alignment is what syncs your steering wheel with your wheels. It ensures your car will drive straight when your steering wheel isn't turned.
Either the road is slanted or your wheels are out of alignment
Have the wheels balanced. Get a 'front end alignment' done on your vehicle.
suspension or steering wheel
It has independent suspension and the vehicle may be out of alignment, over weight or the springs are weak.
Unless it has independent rear suspension (which I doubt) there is probably no adjustment for rear wheel alignment.
With a $5,000.00 piece of equipment. Take it to an alignment shop and dont pay more than $100. Actually call a couple shops and compare prices... It is not your steering wheel out of alignment but you wheels...
If it happens when you are driving fast (60-70 MPH) it could be that your wheels are out of alignment.
Alignment: alignment is positioning of the steered wheels to achieve directional stability during straight ahead position, perfect rolling condition on steering and recovery after completing the turn. Basic factors or angles involved in an alignment are suspension height, caster, camber, toe-in, toe-out, Steering axis inclination (SAI) and turning radius. It is also referred as a wheel alignment.There are three more factors which are affect alignment are thrust angel, scrub radius, set back.All these factors affect steering effort, ride quality, steering stability and tire wear.Here are the indications that car may need an alignmentUneven or improper tire tread wear.Your car pulls or drifts to one side.Your steering wheel does not return easily after a turn (Poor returnability).Excessive play in steering.When you go for wheel alignment of your car it consists of adjusting the angle of your wheels so that they are perpendicular to the ground and parallel to each other or to the manufacturer's specification. Proper wheel alignment reduces tire wear, improves fuel economy and handling. So you need to do the wheel alignment every 7000-10,000 miles.In regular wheel alignment adjustment of toe-in and toe-out is required.In case of any accident or any major case it is required to do full wheel alignment which consists of adjustment of all angles.
Many things can cause steering shake. Wheels out of balance. ( including rear wheels ) Tryes out of round. Worn steering components. Worn suspension components. Even loose wheel nuts/bolts. Get it checked out for safetys sake.
Your wheels are probably out of alignment. You need to have the camber, caster, and toe out checked and adjusted. A failed or damaged component in the steering system is another possibility.
Sounds like your car might need either an alignment or the wheels have to be balanced.