You may see the following error (or a similar error) when you try and start your Virtual Machine or use your VM software:
Those errors appear if a particular setting isn't enabled by default in your computer's BIOS.
In order to fix this, you'll need to boot into the BIOS of your computer and enable intel VT-x. This setting might be called AMD-v if you are using an AMD machine.
Booting in the BIOS differs from computer to computer: to boot into the BIOS you will have to restart and hold down a particular key as the computer starts up. The key will depend on your computer's manufacturer or motherboard, so you will have to perform a Google search to learn what the particular combination is for your computer.
Note that on Windows 8+ you will sometimes have to hold SHIFT while clicking on shutdown, and then on the next startup hold the right key to boot into the BIOS, otherwise the computer will start too quickly for you to have time to press the key.
Once you are in the BIOS menu, you often have to use the keyboard to navigate rather than a mouse: sometimes a mouse works, but often only the keyboard will be used for input.
You'll need to find the intel VT-x setting (this setting might also be called AMD-v or Intel Virtualisation Technology or just VT-x, it varies from computer to computer), highlight it, and enable it, then save and quit. Then you can boot back into your computer as per normal and try running the VM again.
Each BIOS might be slightly different, so we aren't able to provide exact step by step instructions, and it may take some research online to discover the particular way of updating this setting in your computer. It's a bit technical, but if you've never booted into your BIOS before it's a great thing to know how to do.