music copy rights

some of the copyright and public domain laws are

you have the rights to it as soon as you write it you can have it appovered by the goverment.
 you can have the copyright till you die or 75 years and the copyrights mean that you can't use the song or the words to alter it if you use it in public or in your name.
public domain is were you can use that information for your use and the year for that is 1922.

 i go my info from http://www.rbs2.com/copyrm.pdf