Snowy,
I don't know if you do or don't have any Sims living in the house, it doesn't sound like you do. But just to build on 10 Poker Flats, try this.
(1) Start up the game, and click "New Town" then "Twinbrook" (this won't affect any of your saved games, now).
(2) Use the "..." (Options Menu) on the control puck and select "Edit Town".
(3) Click on "10 Poker Flats" and once it's selected, click on the "Build / Buy" button.
(4) Work on the house, as you normally would.
(5) When you are satisfied, on the "..." you need to go back to "Edit Town".
(6) Click the lot again, and save a copy of "10 Poker Flats" to the Library, with the "Save Copy to Library Button".
Now you've a copy of the house in your game's Library, where you can place it into any game you are playing (as long as the lot size works).
Hope this helps, if not ... I can post some pictures. As Pam mentioned, if you're having trouble with specific building issues, you'll need to provide much more detail in your question.
-- Happytime