This link has by far the most well documented guide to encryption and decryption in C#. It uses the Rijndael Class.
There are three different enryption class for AES in the .NET framework. AES is a standard of Rijndael.
When I get some more time I will write a bit more about encryption in the .NET Framework. I can recommend Pluralsights course on encryption in .NET.
took me a few years to find this article but thanks for writing it up. The links are excellent resources.