Security - Save User Profile Data Locally And Securely?

I am creating a VB.NET application for a Calculus class as a little side-project. It requires user profiles that are saved locally in the program's main files. I am using 2 separate classes to access the user profiles right now.

The first class is called Config and it is used to manipulate the basic config file which contains lesson document paths, settings, and user profile names.

The second class is called User and it is used to load up user profiles from a profile directory where user data is saved in separate text files.

The Config class retrieves the user names, and user profile text file paths. This text file path is then handed off to a User object that can then load up and interpret the file.

how should I format the config file and user files so they are secure enough that someone can not easily retrieve or manipulate data?

Here is a sample of how I am reading the text files:

Dim userList() As String = {Nothing}
If My.Computer.FileSystem.FileExists(configPath + "config.cfg") Then
Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser(configPath + "config.cfg")

[Code]....

The problem isn't reading the text file, I am just not sure how to make it secure. I was thinking about first parsing the entire file to translate it from 'encrypted' to text, and then save it as a temporary file which I would pass off to the above code, then delete the file immediately afterward. As for 'encrypting' (is that the right word for this?) the file, I could maybe bit-shift each character using a key that I would save at the beginning of the file.