how do i use Obj Exporter script?

Trying to use it and i get a “must derive from monobehavior” message

i assume i need to call it through another script. how do i do that? can it be used in game?

“Either call ObjExporter.MeshToString() to generate a text string containing the obj file or ObjExporter.MeshToFile() to save it directly to a file.”

Make sure that the script lives in a folder called Editor. You should now be able to select an object with a mesh/mesh filter in your scene window and use the custom menu item created by the script to export your object to .obj

Are you sure you tnot talking about the "wrapper " version. I’d like to know how to use the multi uv set version

If you want to export an object from code and not use the Unity editor menu, use this method:
http://forum.unity3d.com/threads/89842-How-to-use-ObjExporter?p=581367#post581367

There is a example to export http://wiki.unity3d.com/index.php/ObjExporter