can't pick up dll's or namespaces from .dll or .cs files

I am running Mono from the command line using gmcs and can compile and run simple programs using the .NET system references but cannot pick up  my own dlls or namespaces in .cs files with the
using myNamespace; directive.
or
using myDll; directive

These files are sitting in the same directory as my main file so what do i need to pick up dll's or namespaces ?

It always gives the error : The type or namespace cannot be found. Are you missing a using directive or an assembly reference ?

Is there a command line option when compiling or something i need to do to explicitly add a reference?

yours hopefully,

 Elise