If it is a domed colony, you have 2 options. 1, build an Atmospher Converter (requires Planetary Utilization 9 or so, IIRC). 2, get some population of a race that breathes the atmosphere of the planet in question. Move some of them onto the planet and move all of your population off of it. The dome will disappear, and you get 5x more facility slots. But if it is a non-domed colony, you can do nothing to get more facility slots.
BTW, since you seem to be having so much trouble with the tech tree, Planet Utilization requires level 1 of a Theoretical field called Planetary Engineering.
How about doing a search on the forums for "tech tree viewer", I know someone wrote one...
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