Do you mean you got your first "house" through the housing quest, but want to buy a second? If so, visit the house you want in the Crown store, through the in game map, through the housing option of the collections tab, or by visiting the house you want.
Once inside enter the housing editor choose to buy for crowns or gold.
Sorry if I've misunderstood what you were asking for.
#1 tip (Re)check your graphics settings periodically - especially resolution.