Phonegap, iPhone and SQLite database

I'm trying to develop my first iPhone app using Phonegap and SQLite database. My app is simple but don't know how to get started. My app has 2 dropdown list. When the user selects one of them the other dropdown list will reset. Then user will click on Submit button and I want to search the database and display the result.

I've never used the SQLite database and I would like to know in which folder should I keep the database file. The database file is small and will be stored on the device. The database is already populated. User will not add,edit or delete data but only search based on what value was selected using dropdown list.

Can someone tell me how to do this using JavaScript. Pleas note this is my 1st ever app so please be patient with me. I'm struggling to get started. Thank you for your time and advice in advance.

Joe Green