Hola.
Copiado de la ayuda:
Código Delphi
[-]
This code fills each cell with a number. The numbers are arranged in consecutive order by rows.
procedure TForm1.Button1Click(Sender: TObject);
var
I, J, K : Integer;
begin
K := 0;
with StringGrid1 do
for I := 0 to ColCount - 1 do
for J:= 0 to RowCount - 1 do
begin
K := K + 1;
Cells[I,J] := IntToStr(K);
end;
end;
Como ves tienes que poner las coordenadas de la celda
StringGrid1.Cells[columna,fila] := Edit1.Text;
Un saludo.