Tutorial for creating website using existing MySQL db?
It's not too hard. Assuming Drupal 7 and a one-time import:


Create a new content type in Drupal with the fields you want
Export a CSV file of your records with a header row from your legacy database with the fields you want.
Use Feeds to import the csv file.  You will setup a mapping between the csv fields and your content types fields (from within the Drupal UI).  This is pretty straightforward and the feeds module guides you through it.
Feeds will create one node per record (line) in your csv file.


Now if you will continue to use your existing database and want to import new records as they are added, I believe Feeds has some support for this but I haven't personally used it.