Gabriella_KF :
I use Windows 10 Mail on my PC. I simply cannot find the way to create new folders where I can move my e-mails according to different subjects/topics from the Inbox. I would be grateful for some advice, because otherwise I think Mail is OK. Thank you!
That's because folders don't exist in the mail app!
Yes, you heard right, the mail app actually doesn't do anything other than access what your online email account already offers. If you need that functionality, you have two options:
1) Go to your email's website and set up folders and sorting there
2) Buy Office 2016 and use Outlook (or any other full fledged desktop mail client)
Folders aren't really useful anymore thanks to performance improvements in modern mail applications, you can put everything in an archival folder and then search for what you want. It's usually faster than sorting, unless you have enough that you need to do both.