I'm trying to add models to my game to make it more enjoyable, so I did a test to try and get a model to work. I was able to add a model to the editor but it didn't look at all like the preview on the site. I'm new at this so I didn't know the models didn't already come in color ^^

How do I get the models from the site preview to look like the models in the game?
Also, are models not able to be Detail Brushes? I tried to make the model a detail brush at first but every time it loaded my test map it would reload it. Again, and again, and again.
Edit: Well, while I'm waiting for a reply. I'm downloading a free model editor. Maybe the model I downloaded doesn't have color and if I add color then it will work in the game.