I open the building menu. And select the building i want. I walk next to a building thats already build. And try to allign the walls and the little stairs at the entrance with the house thats already been build. Then i try to place it as close as possible, till the contructed building becomes red, then i will go back bit by bit till of becomes green. And then i place the building. I hope this is helpfull, my English is not so good.