Can't get the centos-gnome.vdi. I have extracted the exe file. My system is Windows 10. I didn't have any issue getting virtualbox to be installed and run.
I said I already have virtualbox installed and downloaded cenots-8.1-1911-x86_64-gnome and extracted the vdi. When I want to start centos to locate the vdi, although I have the extracted file is folder on the desktop, I get a message that the vdi couldn't be found.

A .vdi file is a VirtualBox Disk Image being Virtualbox's native disk image file format. A .exe file is a Windows executable file. You have to either create a virtual machine or download/copy the virtual disk image from somewhere and add it to an existing virtual machine.

In any case, if you're using Windows 10, then you'd be better off asking on a Windows forum, as this is a Linux forum.

What do you mean by can't get centos-gnome.vdi or by extracted the exe file?

If you downloaded a VDI image from somewhere, where from and what CentOS version?

Basically, you need to create a new virtual machine by selecting new in VboxManager and then select the vdi image as the hardware instead of creating a new one.

If you did not download a VDI image you can download an install ISO file and install CentOS just like you would with a real physical computer.

VirtualBox manager is similar with either operating system so I consider it agnostic.

Maybe as you said, i should go to a window forum. I guess, this site is above my IQ

Where did you download cenots-8.1-1911-x86_64-gnome vdi image?

When you created the virtual machine using the vbox manager wizard at the hard disk you should of selected using an existing virtual hard drive file. The little folder icon just to right will let you pick the VDI file from anywhere. The location of the desktop is C:\Users\USERNAME\Desktop.

I would not keep the VDI file on the desktop.