a selection that becomes cell

I must make this:
1. to convert one selection (fence or other) in cell
2. to put the cell within a specific one file dgn (mylib)

you can give one hand to advise to me queli functions to me to use?

es:
for point 2I have thought next to
object.AttachCellLibrary CellLibraryName [, ConvertFromV7]
but for point 1 I do not know like making

note:
the file dgn (lib) are not opened or active

i use thi code but not working:
.....
_ElementEnumeratorPtr el_enum;
_ElementPtr el;
_CellElementPtr cell;
Point3d p;

_FencePtr selection = m_spApp->ActiveDesignFile->Fence;
el_enum = selection->GetContents(true,true);
SAFEARRAY *arrElements;
arrElements =el_enum->BuildArrayFromContents();
cell = m_spApp->CreateCellElement1("cella",&arrElements,&p,true);
cell->Color = 111;
cell->Redraw(msdDrawingModeNormal);
m_spApp->ActiveModelReference->AddElement((_Element*)&cell); //crash
....


TNKS