Working with Arraylists

[Ajb181]

Hi team. Im am trying to convert an arraylist of an arraylist to a array of byte[].

but unable to get it to compile any help would be great.
Array abData = new Array[Data.Count];
for (int i = 0; i < Data.Count; i++)
{

abData = (Array)Data;
byte[] DataToSend = new byte[0];
// DataToSend = abData[1];
m_ComPort.Write(DataToSend, 0, abData.Length);
while (M16CCheckStatus(m_ComPort, 100, CMDS.PROGRAM) == M16CMessages.STATUS_BUSY)
Thread.Sleep(10);
}