How to perform file encryption using 128-bit AES I am confused. How can I encrypt a file using 128-bit Advanced Encryption Standard?
Do I need only to encrypt the file name and it's content or is there something that I need to do to encrypt it? Is there something that I will need to extract to the file to encrypt it?
For example, I want to encrypt an MS Word file or a PDF file.
It is easy to encrypt a file if the file only contains text, but what if there is a image in a file? How do I go about that?
You are right to be confused, because you could just as well have asked "How can I encrypt a file using a CPU that supports xor, shifts and rotates?" The answer is that of course you can, but there is obviously a lot more to it, if you are going to do it right.

AES is just a standard block cipher primitive. The only thing this standard tells you, is how to transform a single 128 bit block using a key, into another 128 bit block. It doesn't tell you where the key is coming from, or how you are going to process any data larger than 128 bits. Those aspects have to be specified as well, and one example would be password based encryption as in PKCS#5 PBES2 with AES-CBC-128 combined with PBMAC1 with HMAC-SHA-256.

When reading the technical specifications of consumer software or business software, it is not that uncommon that the only thing specified is the block cipher primitive, such as "128 bit AES". In my experience this is often due to either of the following reasons:


The software developers don't have a clue about cryptography and are actually using AES-ECB-128 with a key that embedded as a constant in the software.
The software developers are using a proper file encryption scheme but specify only the block cipher primitive because that's the only buzz word that they thought was necessary for marketing reasons.
If the software is based on legacy software that used a scheme with e.g. 3DES, stating that they use "128 bit AES" might simply indicate that they use the same scheme as before, but have just substituted the block cipher primitive.


If you interested in how some existing software is encrypting files, just knowing that the software uses AES-128 is consequently not enough. If you are interested in which schemes and algorithms to look up if you were to write such software yourself, you have to be a lot more specific about your security requirements... 


What's the relation between the person or entity encrypting the file and the person or entity decrypting the file?
Exactly what bad things do you hope to prevent by encrypting the file?