working on hashing algorithm SHA-2

I implemented SHA-512, and I don't really get what you don't understand in the description. The message must be padded with a '1' bit, then enough '0' bits, and finally a 64-bit value which indicates the message length in bits. This is also what is described on this wikipedia page (https://en.wikipedia.org/wiki/sha-2). When they say "append length of message (without the '1' bit or padding)", it means that the length value is the length of your message without the padding bits, it doesn't mean that you don't add the padding bits themselves to the last data word.