how can i change print character size or font.

hi,
i use .net and symbol mc3000 pocketpc and seiko sp2400 printer.
i can print any thing.
my code is

Try
PortSettings = New Serial.HandshakeNone
MyPort = New Serial.Port("COM1:", PortSettings)
If MyPort.Open() Then
For say = 0 To dTable.Rows.Count - 1
strline &= Mid(DGliste.Item(say, 0), 1, 7) & Space(9 - Len(Mid(DGliste.Item(say, 0), 1, 7)))
strline &= Mid(DGliste.Item(say, 1), 1, 30) & Space(33 - Len(Mid(DGliste.Item(say, 1), 1, 30)))
strline &= Mid(DGliste.Item(say, 2), 1, 7) & Space(9 - Len(Mid(DGliste.Item(say, 2), 1, 7)))
strline &= Mid(DGliste.Item(say, 3), 1, 7) & Space(9 - Len(Mid(DGliste.Item(say, 3), 1, 7)))
strline &= Mid(DGliste.Item(say, 4), 1, 7) & Space(9 - Len(Mid(DGliste.Item(say, 4), 1, 7)))
strline &= Mid(DGliste.Item(say, 5), 1, 7) & Space(9 - Len(Mid(DGliste.Item(say, 5), 1, 7)))
strline &= Mid(DGliste.Item(say, 6), 1, 7) & CrLf
If i > xtotal Then
MyPort.putdata(strline)
strline = ""
MsgBox("Plase new page !")
i = 0
i += 3
End If

i += 1
Next
MyPort.putdata(strline)
end if
Catch ex As Exception
MsgBox("Error" & ex.Message)
End Try
MyPort.Close()

how can i change font or charecter size. i want use to small size.
thanks regards.