To export.... select an item, go to the drop down menu "3d view" select "export to obj format", browse to a folder where you wish to temporarily store it, then go to drop down menu "furniture", choose the option "import furniture", scroll to your chosen folder, select the item with the .obj extension, not the .mtl, follow the instructions to import it, remember to check the box "add to catalogue" in the 3rd screen. You will need to do this for each item.