One of the easies ways to store byte array in a text form, let's say in the text field of a database, is to use Base64 encoding. It's standard , it's easy and there is a nice support for it in .NET. Just use ToBase64String and FromBase64String.
byte cypherText = enc.Encrypt(plainText, key);
string sEncodedAndEncryptedText = Convert.ToBase64String(cypherText);