An tutorial written by Seth Kenlon, published in opensource.com gives a detailed introduction of Kdenlive time line. Kdenlive is a non linear video editor developed specifically for GNU/Linux, Mac OS X and BSD systems.
Editing in Kdenlive is done both in the monitors and in the timeline. Your initial cuts are made while reviewing your footage and placing clips into the timeline in the order that you want your movie to be seen. Once the initial cut is done, though, most of your time will be spent in the timeline.It doesn't take long to get comfortable working in the timeline, but it does take a little bit of work to get efficient.First of all, the keyboard shortcuts in Kdenlive leave something to be desired. One of the best things you can do for yourself early on is go through the Settings > Configure Shortcuts... panel and come up with some shortcuts that don't require you to have an extra two fingers.