I think what you're asking is how to read text files as opposed to binary files?
It just relates to how you deal with things like new lines, tabs and other special characters.
All files can be read using the FileStream object. This object allows you to read and write byte arrays to/from a file. This would be your option for a "binary" file (although you could read/write a text file using this object).
For text files you can use a StreamReader or StreamWriter. This allows you to read/write text files in a logical way, i.e. one line at a time into a string variable.
At the lowest level all files are stored as binary, it's just a matter of how you choose to view that file when reading or writing.