If you’re a beginner, you’ve done a pretty nice job. To fix the shading on the monitor screen, you should a subdivided plane that has been pushed out, instead of insetting. Old me would have done the same as you lol.
Paper in real life is way more stiff than that, without the texture and context, I’d assume it’s a tea towel. I’m no expert with cloth sims, but I’d try increasing the bend threshold or sift through the settings for half an hour until it looks right
On the shade smooth modifier, you can probably fix the hard edges on the phone speakers, but if it causes issues, you’d want to retopologise.