passing values to a vbscript (asp) function

How do I pass values to the following variables.

<SCRIPT LANGUAGE="VBScript" RUNAT="Server">

Const SESN_GIS = "GIS_SESSION"

Function GISDispatcher_RequestMap(ByVal TheId,ByVal topleftX,ByVal topleftY,ByVal brightx,ByVal brighty,ByVal msh,ByVal msw)
'On Error Resume Next
GISDispatcher_RequestMap=Session(SESN_GIS).RequestMap(TheId,topleftX,topleftY,brightx,brighty,msh,ms w)
End Function

Function GISDispatcher_RequestVectorMap(ByVal TheId,ByVal topleftX,ByVal topleftY,ByVal brightx,ByVal brighty)
'On Error Resume Next
GISDispatcher_RequestVectorMap=Session(SESN_GIS).RequestVectorMap(TheId,topleftX,topleftY,brightx,br ighty)
End Function

</SCRIPT>

the variables in this function are topleftx, toplefty, brightx, brighty, msh,msw.

Also how do I return values back from an asp function and send back to the calling asp routine.