In short:
1) Declare a streamreader to read your file
Dim tRead As System.IO.StreamReader
2) Open your file
tRead = IO.File.OpenText(filename)
3) Read your file (at once or) line by line
readstring = tRead.ReadLine()
4) Extract whatever you need to extract in (multiple) strings.
writestring = "...."
5) Write your new file(s)
IO.File.WriteAllText(filename2, writestring, System.Text.Encoding.Default)
6) Close your file
tRead.Close()