[AND_REY]

Для начала так:

Код:

procedure TForm1.Button1Click(Sender: TObject);
var
 a,b,i,j: Integer;
 Mass: Array of Array of Integer;
begin
 a:= StrToInt(Edit1.Text);
 b:= StrToInt(Edit2.Text);
 SetLength(Mass, a, b);
 For i:= 0 To a - 1 Do
  For j:= 0 To b - 1 Do
   begin
    Mass[i,j]:= 0;// Ëþáàÿ îáðàáîòêà.
   end;
end;