1 2 3 4 5 6 <-- circumstances/context \_ | _/ \ | / 7__ 8 ___9 <-- actions/events/reactions \ |/ 10 <-- theme/focus / |\ future | past | presentcard 10 is the "theme", the overarching happening/event/mood/whatever common to all the periods; If you look at the cards on the left side of the triangle, 1 and 2, 7, and 10, you get some past happening. Same thing for the present and future. There's also two weird auxilliaries: 7, 8, 5 and 6 - "prophecy"; and 1 and 2, 8, 9 - "nostalgia". They're an indication of how past events and present actions affect future actions, and how past and current actions affect future situations. Sometimes they seem useful, sometimes they ain't.
A sample reading I did will hopefully clarify this giant mess:
QW, I KP, 6S, 5W, 2P, World, 9W, Star, AW, I NP (plus I PC + 8P for clarification)
Past: inverted King o' Pentacles is melancholy and distrust, and Queen of Wands is ability/potential; 9W is betrayal, divisiveness; I NP + I PC + 8P (the theme for this reading), small mindedness and lack of conviction, with distraction, emotional excess, and confronting your circumstances or not. The overall past reading is "lots of ability (but no faith in it), mixed with Drama equals massive worries about one's place in things".
Present: 6 of Swords + 5W, "courage in doing work on your own"; Star, "hope for the future", and when adding the theme from above: "Starting to believe one's own abilities, there are now worries about if what's being done is good enough."
Future: 2P + World, "seeing the previously unnoticed connections of things"; AW, "actually doing something about them"; add the theme, and the reading is "people may not accept the new, exciting things you're doing that fulfill you."
I was gonna put up the bizarro reading for myself that I can't interpret, but I'm tired and in a scant eleven hours I get the tattoo on my back filled in, so I'm gonna go snooze.