As Baba said above, it's best to get your feet wet by looking at some of the original NWN models, or even someone else's models.
Assuming you have a model loaded...
Select the modelbase, in the image above it is the white object you see in the Perspective View. Select the Modify tab from the right-side panel. That will open the modelbase rollout. The Export section of the rollout I have highlighted is where the majority of the export functions are contained. First thing is export directory. You can use the Browse button to change the export directory, or the Reset button to set the export directory to its default location. Below that you see two buttons, Export Model + Anim and Export Geom Only. If you have animations in your model, use the first button. If you don't have animations use either button. If you have animations, but don't want to export them, use the second button. The checkboxes should be left at their defaults until you are more comfortable with the process. If you get a "Failed Sanity Check" popup window, you can press "Yes" and it will attempt to export your model. Immediately after that you should press the View Sanity Check Results button from the modelbase rollout. This is one of those situations I mentioned earlier regarding Windows 7 permissions. If it was able to write the Sanity Check file, pressing that button will open up the file so that you can see what may be wrong with your model. If it was not able to write the file, you will get nothing when pressing that button and you will need to fix the permissions the sanity directory has.
Enjoy,
MDA
