First, build a lab.
To do any research, you need to press F2 (quite obvious, but I suppose I should mention).
When, for example, five labs are completed, the background behind first five rows of research options is highlighted.
(if it's not, you're either looking on the wrong research tree or you've build a wrong structure or the structure is offline (planet lost, phasic barrier active etc..)).
When you have enough resources to conduct a research, the research button will get highlighted.
