Uh... you forgot many important things like: end., implementation, interface, type.

Do you know how to write a unit? I'm asking because if what you gave is a snippet, you could at least mark where you snip so we know it's a real unit.

Firstoff, this isn't a managed language, so you do have to reference other units. Like so:
Code:
unit unit1;

interface

uses unit2;

implementation

end.
Code:
unit unit2;

interface

uses unit1;

implementation

end.
Otherwise this'd be a problem for you.
Code:
// Secteur d'activit?©
TActivitySector = class
FName : string;
// The ware produced by the industry
TWare &#58; TWare; // <-- You assign to FWare, not TWare. ;&#41;
constructor Create;
end;