I need to know also...
I don't even know how to terraform to T1...
there are probably a number of guides out there about this but i'll give a short version anyway. (or at least try to make myself sound smart anyway )
first you need to switch the mini-map to the terraforming grid(graph? scope? whatever) either by clicking the mini-map/terraforming toggle(the small button to the right of the planet name. it looks like a globe) or it will automatically switch when you select a terraforming tool or your abduction beam(which can be annoying when you don't want it to).
you will see a crosshair on the left side of the grid (graph...whatever) and a small yellow dot somewhere either in or around it.the closer the dot is to the center of the crosshair the closer the planet is to being a t3 planet. you can move the dot vertically by either increasing the atmosphere (moves the dot up) or decreasing it (moves the dot down). the dot can be moved horizontally by increasing the temperature (moves the dot to the right) or decreasing it (moves the dot left).
as you move the dot around, pay attention to your messages. when it says you have increased the planets t-score, start filling out the food web by first dropping your plants (small,medium and large), then 2 herbivores and last a carnivore. as soon as you have your 3 plants down you will get a message saying you have stabalized the planets t-score, which means that as long as you don't try to move the dot in the wrong direction, the t-score will remain at the level you left it at.
as gremlin said, you will need 9 different species of plants (3 each of small, medium and large), 6 different herbivores, and 3 carnivores to max out both the planet's t-score and colony potential.
but here are a few tips for this:
while you have to gently place herbivores and carnivores on the planet's surface, plants aren't as fragile. just spit 'em out and they'll be fine.
also you don't have to leave any of the plants or animals you place down for the foodweb to remain full. as soon as you place one down you can immediately pick it back up. this way you can always have what you need to terraform the next planet. though i would recommend keeping about 5 or 6 of each specimen type just in case of a mistake.