Avidemux is a free and open source multi purpose video editing software. It is licensed under GNU General Public License and works on different platforms. The user interface is easier to use then most other video editors. Avidemux supports a lot of audio and video formats and has subtitle handling. You can cut, append, add filters and re-encode into different file formats. There are tutorials on their Wiki page to help you get started with Avidemux. If you have any questions there is also a forum page that addresses a lot of them. Check out the video editing app Avidemux on their website.