HII ! im download one of your houses but im not sure how to get it to go on the game, could you give me instructions on how to do it if your not to busy please

There are two ways:

Sims3pack:

You can download the sims3pack file and install it using the sims launcher (it will show up under your downloads).

Package  

Download the ***.package file, and unzip it directly into your library which is usually located in your Documents folder …sims 3/the Sims 3/Library/ …

Once you’ve installed it, launch your game.   When you go into your world, go into the control panel on the bottom left and select “Edit town”.

In “Edit Town” mode, then you can select the lot from the houses in your library. The newest lots you install are at the beginning of the list.  

In your world, now you can place the house on an empty 30×30 (or larger) lot.  

I hope that answers your question. Enjoy the house. :)