Another C# Array of objects question

I'm having trouble accessing array list members contained within a class.  First here is the class:

using System;
using System.Collections;

namespace Inhallation
{
      /// <summary>
      /// Summary description for clsChamberInfo.
      /// </summary>
      public class clsChamberInfo
      {

            
            public int ChamberID;
            public bool Active;
            public string ChamberTitle;
            public ArrayList arAlarmInfo = new ArrayList();
            public ArrayList arDataCapture = new ArrayList();
            public ArrayList arLastData = new ArrayList();
            public ArrayList arNewData = new ArrayList();



            public clsChamberInfo()
            {
                  //
                  // TODO: Add constructor logic here
                  //
            }

            public clsChamberInfo(int chamberid, bool active, string chambertitle, ArrayList [] aralarms)
            {
                  this.ChamberID = chamberid;
                  this.Active = active;
                  this.ChamberTitle = chambertitle;
                        
            }

            public void AddAlarm( string alarmname,string uom,int alarmid,decimal lowvalue,decimal highvalue,bool active,int recordid,decimal highwarning,decimal lowwarning, decimal x2, decimal x, decimal constant, int linear, int equationtype, int calculationtype, int displaydecimals, bool activewarning)
            {
                  this.arAlarmInfo.Add( new clsExposureAlarmInfo(alarmname,uom,alarmid,lowvalue,highvalue,active,recordid,highwarning,lowwarning,x2,x,constant,linear,  equationtype, calculationtype, displaydecimals,  activewarning));
            }

            public void AddData( DateTime runtime, int runnum, int startnum, int positionid, int alarmid, decimal parmvalue, int studyid, int sessionid, int exposurerun, bool inexposure)
            {
                  this.arNewData.Add( new clsExposureData(runtime,runnum,startnum,positionid, alarmid,parmvalue, studyid, sessionid, exposurerun));
            }

            public void CopyData()
            {
                  this.arLastData.Clear();
                  this.arLastData.Add(arNewData);

            }

            public void AppendToDataCapture()
            {
                  this.arDataCapture.Add(arNewData);

            }

            public void ClearNewData()
            {
                  this.CopyData();
                  this.arNewData.Clear();
            }



            public override string ToString()
            {
                  return this.ChamberTitle;
            }
      }
}


From my main program, I want to access the members of the arNewData ArrayList.   Here is a function that I am stuck on :

            private void PlotData()
            {
                  for( int i = 0; i<arChamberInfo.Count; i++)
                  {
                        switch(i)
                        {
                              case 0:
                                    waveformGraph1.PlotYAppend( ((clsChamberInfo) arChamberInfo[i]).<-------Stuck here
                        }
                  }
                  waveformGraph1.PlotYAppend(newPos,2);

            }

arChamberInfo is an ArrayList of clsChamberInfo objects.  I want to get to the arChamberInfo[i].arNewData members, like arChamberInfo[i].arNewData[0].  Thanks for your quick help.  I'll be checking back frequently in you need more clarification.  Thanks.