"Who is Logged in" module

[mrcooll]

hi all i want to list all of the logged in users on a page , i did it fine but i have a problem when the user close the browser i cant remove them from the list, how can i get use of Session_End in the Global.asax . this code is in Global.asax

private Code.BL.Users.SysUserCollection users = new Code.BL.Users.SysUserCollection();
public Code.BL.Users.SysUserCollection OnLineUsers
{
get { return users; }
set { users = value; }
}

this code is in BL

public class SysUserCollection : IList<SysUser>
{

    List<SysUser> users = new List<SysUser>();

    #region IList<SysUser> Members

    public int IndexOf(SysUser item)
    {
       return users.IndexOf(item);
    }

    public void Insert(int index, SysUser item)
    {
        throw new Exception("The method or operation is not implemented.");
    }

    public void RemoveAt(int index)
    {
        users.RemoveAt(index);
    }

    public SysUser this\[int index\]
    {
        get
        {
            return users\[index\];
        }
        set
        {
            users\[index\] = value;
        }
    }

    #endregion

    #region ICollection<SysUser> Members

    public void Add(SysUser item)
    {
        if (!this.Contains(item))
        {
            users.Add(item);
            
        }

    }

    public void Clear()
    {
        users.Clear();
    }

    public bool Contains(SysUser item)
    {
        foreach (SysUser user in users)
        {
            if (user.UserId == item.UserId)
                return true;
        }
        return false;
    }

    public void CopyTo(SysUser\[\] array, int arrayIndex)
    {
        throw new Exception("The method or operation is not implemented.");
    }

    public int Count
    {
        get { return users.Count; }
    }

    public bool IsReadOnly
    {
        get { throw new Exception("The method or operation is not implemented."); }
    }

    public bool Remove(SysUser item)
    {
        foreach (SysUser user in users)
        {
            if (user.UserId == item.UserId)
            {
                return users.Remove(user);
            }
        }