Aleth allows you to create flashcards to help you remember anything you want.
Create a new card whenever you learn something new and Aleth will make sure you never forget it.
You should review your cards every day (it's OK to skip a day but it means you'll have more cards to review the next day). Reviewing cards usually takes only a few minutes per day.
Aleth was designed to be used as described in this (rather long) essay.
Aleth's focus is on simplicity. If you would like more features such as creating separate decks and sharing them, I recommend you try Anki which has a large number of premade decks for a wide variety of topics.