Chrome Remote Desktop is a great tool to share your screen with anyone for free.
It’s very easy to use. First you need to visit remotedesktop.google.com and install the Remote Desktop extension. If you already use Chrome as your browser and are familiar with extensions you can add it as usual through the Chrome Web Store.
You don’t need to use Chrome but you will need a Google Account. If you don’t have one already it will prompt you to set one up in your regular browser before accessing the sharing page.
Once done, click on the extension or visit remotedesktop.google.com/support/ to generate the share code.
The person you want to share your screen with also clicks on the extension or visits remotedesktop.google.com/support/ and enters the share code into the box to remotely connect with your computer.
I use this all the time with colleagues and clients as it’s simple to use, reliable and free.