The names on the left show who has responded. The green days and times in the grid show when everyone is free. If you see no green at all, start clicking on names at the bottom of the list and 'exclude' people till you find a match. The little red dots are near misses - how many people can't make that time. When more than four can't make it, you will see a little number showing how many for whom it is a problem.

Mouse over a date or time: the names will change colour to show who can or can't make it. Hover for a moment and a popup will show a summary. Mouse over a name to see their full availability and comment. Click on a name to fix their availability on the grid and see more options in a popup. Click on a time to open a small window with a full report.