You can import a png image into videoscribe the same way you import any other image, but it may not "draw well in videoscribe. If you want an image to "draw" well, then you will need to find properly made SVG files or make  your own SVG images in accordance with the guidelines in the SVG tutorials on this website.

For example:

http://blog.videoscribe.co/how-to-make-a-svg-for-videoscribe-in-adobe-illustrator/

http://help.videoscribe.co/support/solutions/articles/1000033714-create-your-own-images

Detailed tips for Making SVG Images Draw Well (2017 update)

-Mike (videoscribe user)