Please help getting my 'learning' (but real) project going in Rails

learning fast, but still a newbie with Rails. I have a real world
project to do and just finished converting the data and laying it out
in mySQL. Essentially what needs to happen is this:

  1. User plugs in location (zip code) - that information is stored and
    even displayed on screen for the entire session (think yahoo yellow
    pages) - So anything you do thereafter is filtered on that location.

  2. basic look-up - user then is free to put in a medical code or the
    affiliated description for that code and a look-up/search is performed
    on that information with respect to the location (i.e.: miles from)

Essentially just a simple search page right now with the added
complexity of a stored location. I have about 6 tables although I
believe only one or two will be used for this initial screen. Can
anyone help me get started here?

What does the code look like to enter in a zip code, do a quick search
to validate the location and maybe return/display the actually town (I
have the data) more importantly STORE that location to be used for all
look-ups? Would this be in the controller with a corresponding view
of just this piece?

What does the code look like to build a basic look-up and return
results to the same screen? Controller?

ILLUSTRATION:

First box you enter zip code 12345 - under that box systems returns
your location is = SOMEPLACE, USA
That is also stored
Second box you enter ‘heart surgery’ PRESS ENTER
System will return for example: the number of heart surgeries for that
location (I have the data)

I have several books including the Agile Web D. with Rails
book, in the process of reading now.

Any help is appreciated - just want to make sure I am starting this
thing out correctly using the ‘rails way’