Learning new cards
When you're asked questions for the first time, Anki is in learning mode. This mode is designed to help move new information into your short term, and then long term memory.
In learning mode, you are given 5 choices for how well you remembered. The first two choices delay a card for a default time of 10 minutes. About ten minutes after you have failed a card, it will appear again. For the first few repetitions, there is no need to spend too much time trying to memorize each card as it appears. You'll learn some of the material with little effort, simply by being exposed to it multiple times. But some material is more difficult to memorize, and after a few failed attempts, you may want to think of a mnemonic] to aid memorization.
Also, don't be afraid to choose to repeat the card in 1 or 4 days multiple times. You are the best judge of your memory. Once you have reviewed enough and feel confident that you will remember the card for a week, then you should choose '4'.
If you find you're seeing and forgetting the same cards many times over, consider slowing down and inventing some mnemonics for the most difficult cards.