Hi, Ron. Congratulations on finally moving up!
Techie is correct. With Windows 10, you have a digital license or a product key. So, first see
Activation in Windows 10 - Windows Help. Also see
Find your Windows product key - Windows Help. Since it is an OEM (Dell) device, there will be a product key. By making note of that important number, should it ever be necessary to reinstall the operating system and you are having problems with the activation, you'll have the "magic number".
As techie also recommended, a good backup of your important files, pictures, etc. is most important. Backup is one thing but because of the way things have changed, files that I frequently access, I make sure I have a copy stored on OneDrive. That way, I can access those files from any of my devices, including my cell phone.
Feel free to ask us questions you may have as you make the adjustment to Windows 10.
While I was composing, I see you added another reply. With a bare bones PC with a fresh copy of Windows 10, you don't need to make an exact copy of the HD. It is easy enough to "Create Windows 10 installation media" following the instructions here:
Download Windows 10. Keep in mind, however, that unlike the earlier Windows operating systems, instead of service packs every couple of years, a new build of Windows 10 is released twice a year -- in the spring and in the fall. The current version is 1809 but the next version will be released in May -- the entire operating system so creating a clone of what will soon be an old version won't be all that helpful. Here are the recovery options for Windows 10:
Recovery options in Windows 10