To Draw a white line on a colored background

Hi Keith,

go ahead, Inkscape can do that :)

For a background, a common way is to just use a rectangle, but it's also possible to set the background color of the document.

For drawing a line you can use the pencil / freehand tool or the pen / Bézier tool. Then set a stroke color, remove a fill color, if one is set and add the blur with the slider in the fill and stroke dialog.

To learn how to do this, please see, for example, here:
http://vektorrascheln.de/posts/2015/Dec/inkscape-fuer-einsteiger-teil-ii-praxis-en.html#bezier-curves-and-lines
http://vektorrascheln.de/posts/2015/Dec/inkscape-fuer-einsteiger-teil-ii-praxis-en.html#changing-colors-editing-stroke-and-fill

or in the manual:
http://tavmjong.free.fr/INKSCAPE/MANUAL/html/

or in this tutorial series (esp. parts 4 and 6 in the pdf):
http://dl.fullcirclemagazine.org/issueIS01_en.pdf
Overview of all 'episodes':
http://www.inkscapeforum.com/viewtopic.php?f=6&t=11981

Kind Regards,
 Maren