Ok trying to place a house I saved to My Library, how?

hi can some one help me when i go in to the gallery when i am in the game to put a house down in any of the worlds and when i get ready to exit out of the gallery i can 't put the house down becausethe world id there but it looks like it is in the eving time aboyt to get dark it like ashade bloking me from putting house in world