Convert 3D-Polylines to Solids in R13 (Imported a 3DS file)

Hi y'all,
I am new to both 3DSMAX and Autocad. I recently created a model in
3DSMAX3 and exported it a 3ds file. I imported it into R13 and it
appeared to come over without a hitch. I wanted to do some more
manupaulting of the model (bevels, fillets, etc..) but R13 won't let
me since the model's edges are 3DPolylines and the whole model is not
a SOLID. It's acutally a collection of 3Dpolylines and Polyface
meshes. Did I do something wrong in the export/import operations or
do I somehow need to "convert" the model into a 3DSOLID in R13?
Thank you for any help...
JGG