For some months now, Windows 10 has being around and thousands of Windows users have already installed it already though, through the official update that were being pushed to some Windows 7 and Windows 8.1 users. However, it should be noted that the updates are being pushed to genuinely activated Windows 7 and Windows 8.1 users ONLY.

In this tutorial, I take you through the step by step guides on how to install Windows 10 on your PC. Refer to the guides here on How to Create a Bootable Windows 10 Flash Drive or USB Disk as that would make the fresh Windows 10 installation easier for you.

Now, let's get started!
This tutorial involves the use of a bootable Windows 10 Flash Drive or USB Disk, hence, you should refer to the tutorial referenced above. Also, Product Key would be required to activate your copy of Windows 10 on your PC therefore, you are advised to obtain one or perform a free upgrade. See the Step 4 discussed below for details.

INSTALLING WINDOWS 10 ON YOUR PC

Step 1: First and foremost, backup all of your data to either a cloud-based service or an external hard drive. This is important because this process will most likely clear all the documents on your PC.

Step 2: Make sure your computer meets minimum system requirements for Windows 10 to avoid interruption of the operation halfway through.

ACCEPTABLE PC CONFIGURATION FOR INSTALLING WINDOWS 10:
CPU: 1GHz processor or faster
RAM: 1GB for 32-bit / 2GB for 64-bit
Storage space: 16GB for 32-bit / 20GB for 64-bit
Graphics: DirectX 9 capable video card

Step 3: Get a spare USB flash drive with at least 4GB of free space and make bootable Windows 10 drive out of it by following the instructions here: How to Create a Bootable Windows 10 Flash Drive
Also, DO NOT forget to get the product key ready. See the note below:

Step 4: If you have a Windows 10 product key, you may proceed otherwise, you will need to first go for the Microsoft’s free upgrade offer before you can do a clean install.
Microsoft’s free upgrade offer requires you to be either on genuine version of Windows 7 SP1 or Windows 8.1 Update. And you can upgrade to your free Windows 10 copy by following the tutorial earlier discussed here: How To Download And Install Windows 10 Free Upgrade.

Step 5: Once upgraded, make sure your copy of Windows 10 is activated. You can check this from Control Panel > System and Security > System.

This is important because Windows product keys are tied to the hardware of your computer. Meanwhile, if you have used the Microsoft’s free offer earlier discussed for upgrading your PC from Windows 7 or 8.1 to Windows 10, Microsoft knows the computer hardware you upgraded on.
Hence, once upgraded and activated on Windows 10, you can do a clean install of Windows 10 at anytime – even after completely formatting your hard drive, it will remain activated as long as it is done on the same hardware.

Step 6: With the bootable USB plugged in, boot your PC to BIOS or SETUP. The procedure for entering BIOS or SETUP differs for every computer and hardware.