How to render a self-written widget in Gtk

I've been writing a Gtk+ Widget which plays videos and, using libAV, I can load and read video files but I don't know how to get the frame data rendered as a widget. What do I do to render it? The frame data consists of an array of unsigned chars.

GTK+

You could just find some dogshit from somewhere and throw it at the screen. It would probably look better.