Elora, assume you have a mesh that has some texture UV mapped to it and you also have a collision mesh that is either a box or convex hull shape. When you export them to a .nif file, in Blender's .nif export dialog box, change the collision type from Static to Clutter. Examine your .nif file in NifSkope with Draw Havok turned on. The collision mesh should be blue rather than the red you see for a static. In the CS, define a new MiscItem based on the .nif file you exported. You will also need an icon image. The icon must be 64 by 64 pixels with no mip maps. Although it's not essential, it helps if the background is transparent.
Edit: You also don't need a normal map for the icon image.