In this guide, I will be showing you how you can upgrade from Windows 7 to Windows 10 Pro Insider Preview (Build 10074).
The first step is to download the Installer from the Microsoft website. There should be a [Start the Upgrade Now] button. This should download a file called Windows10InsiderPreview.exe
If you start the installer, you will see the following screen
After the machine will reboot. When it starts again, windows update will start checking for updates.
Until finally, you are ready to update. Don't worry though, there are plenty more waiting to look forward too.
After starting the upgrade process, you will finally see a popup which asks you to accept some 'Important legal stuff' before you can continue.
After this, it will continue upgrading.
Windows will then shut-down to start the configuration process. You should go through the following two screens. You are almost done.
After this, you will see a screen welcoming you back. If you click next and select 'Use express settings'
This should start the final config process in which you will be greeted with a bunch of pretty colours until you finally have your new desktop! Congratz.