probably have it already.)
The basic idea is to go through the deck randomly (by pressing Next card), until
you can recognize all the kana.
Press the Label button to display the name of each kana. Leave it on while you're
first learning; when you start to know the kana, turn it on only when you're stumped. You may also find it useful to start by reviewing this chart of all the hiragana characters.
Click Forget once you are sure you know a card. Then it won't be displayed
as you go through the deck, leaving you to concentrate on the ones you don't know yet.
Press Reset to go back to displaying all cards.
If you view the source for the page, you can modify it to display other sets of cards.