Unlike your typical paint and pencil graphics programs (think MS Paint), vector graphics programs can be somewhat challenging to use as they're not entirely intuitive. Quite a few excellent tutorials can already be found on the Inkscape Tutorials Page. The tutorial I'll be presenting here is specifically geared towards creating or preparing graphics to be used with cnc devices. As with any relatively complex program, it will take time before you can become proficient, but this tutorial should help with the first steps.
You can watch the first part below.