Do you mean this scene, where he's reading the
Red Ryder ad in bed?
There's a watermark on this pic
(that could be cropped out if you want to do a close up of his head/baseball card area) and I'm not sure if it's hi-def enough, but it's a starting point. Maybe you could use this pic to do an image search and zero in on what you're looking for.
*
Ralphie-in-his-bedroom-Christmas-Story03.jpg
*But be very careful about searching for "little Ralphie laying in bed," as the authorities will start adding your name to all sorts of investigative lists!!! 