Check that, my fault, it's the sixth mission.
I have looked everywhere on the internet for a FAQ but couldn't find one. I'm stuck on mission five in Perimeter. The mission objectives say to build the alpha gate and then to charge it. I built it, but I have no idea how to charge it. When I click on the structure, nothing happens, no menu specific to the building comes up. Am I doing something wrong? Any help would be great.

Land your frame - the top left button on its control panel - and it will charge it's 'Spiral', when it gets to 100% then take off again and approach the portal.
Also, http://www.funkylydia.com has some useful information on this game.

I landed ("Installed") the Frame, built the cores on all four marked spots, then the fifth spot where the portal should be appeared. I built the power core next to it (just far enough), but I still can't build the portal.

When I try to place it, it's red. Won't turn to green, no matter what. (Even tried charging the energy up to the max.)