can you help me put a stp. file into autocad 2011
What kind of type you are using software in autocad open file > import > choose .stp file after that save file in autocad.dwg
it tells me "i have selected an unsupported or invalid .dgn file"
usually i have import from .stp to .dwg file and i made it. But If autocad get Warn about unsupport file or invalid .dgn file, maybe you need another support software can put stp to .dwg, you can search on search engine yahoo or google, good luck my friend
I am uncertain which platform you are working with, but Autocad have a free software called Inventor Fusion, which converts .stp files to .dwg files.
The link to the page is http://labs.autodesk.com/technologies/fusion. I have never tried it but at least you have a lead.
I use Rhino as a "translator".
Rhino for me is priceless for its versatility and simplicity of the controls as terminology borrowed from Autocad.