When you use the wall of fragments page, every time you click on a fragment to view it, a new window will open. Sadly this can’t be helped. Just keep closing the windows as you go along and don’t worry… If you add a fragment to your basket it will remain there for you to come back to, unless you delete it directly from the basket
If you are on a desktop you can move the fragments around the screen with the mouse, on the landing page ‘wall of fragments’. On a touchscreen device, like a mobile or tablet, you won’t be able to, so you might prefer to view the shop as grid instead.