@GlassEgret Your photo works as a starting point (and is similar to how some of my photos start) but ideally you want to do some more work on it with photo editing software to get the best out of it.
Like @thegreetingscardshop I’ve done an example of what I’d do with your photo. I’m using (a very old version of) Paint Shop Pro, but there are many different photo editors you can use, some which will cost and some which you can find free online. They’ll all be a little different in what they can do, and name their tools slightly differently, but hopefully most will do the important jobs. Because of that it can be good to just have a little play around on 2 or 3 that you can find online to see which you find easiest to use.
What I’ve done with the photo is:
*Use a cloning tool to get rid of all those bits at the edges that aren’t white (you can fix that at the photo taking stage by using a larger sheet of white as a background).
*Brighten the photo a little - I used the “lights” setting in PSP, but I don’t think that’s common in other photo editors, so brightness/contrast, gamma correction, levels or curves are all other ways you can brighten photos.
*Use the freehand selection tool or magic wand to select the background but not the items - this means you can carry on brightening the background to a clean white without altering the colour of the item (if you brighten that too much the colours can start looking unrealistic).
*Brighten brighten until the background is properly white.
*Once your background is white, you can make the image square by changing the canvas size without an obvious change in background colour. Having a square image means your item won’t get cropped in the thumbnails (or when you’re taking the photos you can just make sure you have enough background showing that you’ll be able to crop down to a square).
*Final step, because I resized the photo smaller as 3872 pixels is much bigger than needed, I also used the sharpen tool just to bring back some clarity.
I know that all probably sounds very complicated if you’re not used to using photo editors, but it’s hard to give a proper step by step guide without knowing exactly which editor you’ll be using. Hopefully it’ll at least give some ideas on what to try playing around with.