The Inksmoto level editor is implemented as an extension to Inkscape, an Open Source vector graphics editor.
Svg of levels build with the 0.4.1 version of Inksmoto are not compatible with this release.
Even if the application windows changed, there's still plenty of stuffs from the 0.4.x and 0.5.x tutorials which applies to the 0.6.0 version, check them out:
Tutorial: First steps
This part of the tutorial learns the basics to be able to create a level.