Can't close paint or open new paint

I've experiemented with paint for the first time today, but now I seem to be
stuck with the first page I opened, I can't get rid of it or open a new file
to try some more designs etc. I've tried removing and reinstalling the paint
programme, but it doesn't make any difference, and I can do anything more to
the page that's still open either - sorry to be so confusing.

I've tried removing the image (which is now just a short line in the corner)
but either it doesn't respond or tells me there are too many programmes
running (I've only got the usual ones running - and it's a fairly new pc so I
haven't downloaded anything extra on it)

Thanks