1) load some data into a table (probably using sqlite) and play around with it using sql 2) read up on some database theory 3) check out a few popular options

1) load some data into a table (probably using sqlite) and play around with it using sql 2) read up on some database theory 3) check out a few popular options: sqlite, mongodb, couchdb and play around a bit more. 4) find a big dataset that interests you, load it into one or more of the databases you want to experiment with, and experiment away by trying to extract interesting data, etc. Notice how each one performs, etc.