How do I register copyright for my songs?

Copyright protection attaches as soon as you fix the song in a "tangible medium."

Though many folks are still under the misapprehension that you have to register your work with Copyright Office to "copyright" it, that hasn't been true for decades. Generally speaking, if you scribble something on a sheet of paper and then someone comes around and copies it, they've violated your copyright in the scribble.

Copyright in Vietnam

On the other hand, if you're just riffing in your bedroom and someone comes by, listens in through your window, and then copies your song, you're probably not going to win on your copyright claim. If you riffed and then recorded it, wrote down the music notation, etc., then you would have secured the copyright at that time.

Note, though, that although registration isn't necessary to protect your work via the Copyright Act, it is a precondition to suing in federal court. So if you write down a song in 2001, discover that someone copied it in 2011, you'd have to register the copyright (even in 2011 or 2012) before you could sue on it. Statutory damages would also be limited to the date you registered onward (i.e., you wouldn't be able to claim statutory damages from 2001 to present).

Source: Quora 

ANT Lawyers -  A Law firm in Vietnam is supported by a team of experienced patent, trademark, design attorneys with qualification and skills handling full range of legal services relating to intellectual property rights in Vietnam. We have specialized in the preparation and registration of patents, trademarks and designs for our clients.