How do I put my whole creation,(house) into a script to sell, as a model?

Just select all of the house, right click it in the explorer window, then click "Publish to ROBLOX"

You're asking for your house/creation to be put INTO a script? I think you are seeing scripts in the catalog thinking they're a model. If you see a yellow script or the Lua symbol. Then the are a script, although if you see a like picture of a man or a house etc then it's a model with bricks.

To do this you get your creation highlight all of it (or if it's in a model just select it) and then right click and press 'Save to ROBLOX' a screen will pop up asking for:-

Name of Model: Description: (Optional) Copylocked/Uncopylocked: (Are other players allowed to take it) Comments: (On/Off)

Then press OKAY. Then you can check your models or your inventory. Remember this has to be done in Studio, not build mode. I hope this helped,

-iFluster