Dee Aussie

Hi I have been downloading some 3d objects to dreamplan. However when I did the import my object is not represented correctly (its in 3 separate little pics) as a 3D. I have tried to redo it several times but still got it wrong . So now I have several objects in my list I need to delete. Does anyone know how to do this? Any advise and how to import properly. I've watched the tutorial several times, but I am obviously doing it all wrong. Help? thanks Dee