I have uploaded the tutorial I have written about making a house for FSX using SketchUp. This tutorial is aimed at the novice developer that wants to build his (or her) first object. It covers the following topics:

• How to gather the information about the building
• How to model the geometry in SketchUp
• How to create the texture from photo material
• How to map the texture on the building
• How to export the building to the file formats used by FSX
• How to position the building at the right location in the world

You can find the tutorial on the FSDeveloper Wiki. I hope it gives you a head start in making your own objects for FSX! Btw, some of the topics are not SketchUp specific by the way, so they might also be useful when you are modelling in GMax or FSDS.