>where is it? In memory?

Yes.

>If I attempt to createobject("ClassName"), I get an error message stating >that "Class definition ClassName is not found".

set classlib to myclasslib
oMy = createobject('myobject')
if type('oMy') == "O" AND !isnull(oMy)
    oMy.show()
else
    wait window "No Go!"
endif

HTH