dynamic dropdown menu - brand new to this

[alpha1]

hi im interested to learn how website such as www.autotrader.co.uk have that drop down menu

 

when when you change make, it gives you a different list in model.

 

i have no experence with javascript or ajax and would love it if you could explain it to me, or direct me to a tutorial.

 

what i want to do is create a database with different car makes, model, varient and year and somehow this to dynamically appear in the dropdown boxs.

 

e.g.

in a table if i have inputed the data  make - ford    model - mondeo varient - 1.6 year -2005

then dynamically an option for ford appears in the makes drop down, when thats clicked dynamically the option mondeo appears in the model drop down etc.

 

isit possible?