The 'Watchlist (Main)' list is like your incoming stash - all athletes added here via their profile pages (using the +Watchlist button) go there. Lists don't allow duplicates, so move an athlete off the Watchlist to another list first, before re-adding them back for additional lists/uses.
No save button required, it auto-saves.
Move athletes between lists by click-holding-and-dragging. Move athletes up-and-down lists to automatically re-arrange (rank) them.
You can rename any list by clicking on its name.
You can have up to 10+ lists, but you'll get a slider bar after 3 due to page-width limitiations.
Clicking the symbol on an athlete will show them in the quickview window, and clicking will remove them off your list.
The Group Share button on each list allows other members of your institution to see and share your lists.