Creating Custom Models

I am new to the creating your own custom model arena and need some help.  I have created a custom frigate factory and need to now how to convert it to the proper file time and then putting it into the game.  Also I how to convert the game meshed into the proper format to bring them up in sketch up so that I can scale my model to the right size.

Any help any one can give me will be greatly appriciated

MyGabby