regarding dropdown listbox loop code

[me dev]

Hi,

I am new to Watir.
I wanted to automate a web application, where there are two dropdown
listbox with each 5 items listed.

The scenario is "Currency conversion".
we have to enter a value in a textbox and select the listed items from
the two listboxes and click OK button and to get the value other
textbox.

e.g. The "XE Quick Currency Converter" section of http://www.xe.com/
1. Go to http://www.xe.com/
2. Enter the currency value (for which we need to get the converted
currency value)
3. Select one option from "From this currency:" dropdown listbox
4. Select one option from "To this currency:" dropdown listbox
5. Click on "GO" button

Here, I would like to get help on the the TWO dropdown listboxes. Plz
help me out to get the loop code, that will handle the TWO dropdown
listboxes.

Thanks,
- dev