Click on a puzzle and enter your settings (letter scheme, buffers, and so on). Once this information is entered, you will be able to submit scrambles and request memo for them. You may also submit scrambles and memo and check whether or not your memo is correct. This can be used to practice execution only, to practice memo only, or for post-mortems in the event of a DNF. If you have any feedback, please provide it on the speedsolving thread.
Your settings for a particular puzzle can be saved as a bookmark. Once you have entered your settings for one of the pages, say 3x3x3, you can click Home on the 3x3x3 page to return here, and then click on another page, say 4x4x4. Doing this will carry over all applicable settings from 3x3x3 to 4x4x4, leaving other settings as default. You can enter the rest of your settings for 4x4x4, and then bookmark that page also to save those settings there.
New: Trainer. Good for practicing execution and/or warming up before a solve. This gives you a memo sequence for a particular piece type which, when applied to a solved cube, returns the cube to the solved state. (Idea due to Roman.)