怎样打开文本文件？该怎么处理

怎样打开文本文件？
新手求教：
有个文本文件aa.txt在程序目录下，格式是每行四个数值，用逗号隔开，有若干行。
怎么读取这个文件，这些数值赋给一个n*4的二维数组

------解决方案--------------------
读取文件

Dim fs As StreamReader
Dim strRead As String = " "

Try
fs = New StreamReader(FileName)
strRead = fs.ReadLine
Do While strRead <> " "
If IsNothing(aryRead) Then
ReDim aryRead(0)
Else
ReDim Preserve aryRead(aryRead.Length)
End If
aryRead(aryRead.Length - 1) = strRead

strRead = fs.ReadLine
Loop

blnRtn = True
Catch ex As Exception
_Err = ex.Message
blnRtn = False
End Try

If Not IsNothing(fs) Then
fs.Close()
fs = Nothing
End If

strRead = Nothing

------解决方案--------------------
Imports System.IO

'读取txt文件
Public Function readtxt(ByVal path As String) As String()
Dim sr As StreamReader
Dim s As String
Try
sr = New StreamReader(path)
s = sr.ReadToEnd
Dim a() As String
a = s.Split(Chr(13) & Chr(10))
If a.Length = 0 Then
MsgBox( "没有数据！ ", , "提示 ")
Else
Return a
End If

Catch ex As Exception
MsgBox( "没有此文件！ ", , "提示 ")
End Try
End Function

'将读取的数据转为2维数组
Public Function array(ByVal a() As String) As String(,)
Try
Dim n As Integer = a.Length - 1
Dim i, m As Integer
Dim b(n, 3) As String
Dim c(3) As String

For i = 0 To n
c = a(i).Split( ", ")
For m = 0 To 3
b(i, m) = c(m)
Next
Next

Return b
Catch ex As Exception
MsgBox( "没有数据！ ", , "提示 ")
End Try

End Function
------解决方案--------------------
参考以下内容：
System.IO.StreamReader
System.IO.StreamWriter
System.IO.TextReader
System.IO.TextWriter
到msdn搜索小例子，
不好意思，以前自己找的都没记住。