Just go to this link. https://experiments.withgoogle.com/chrome?tag=WebGL You will see it is like a gallery, select one of them by just clicking the "Overview button" the site looks like this.

When you click the overview button you will be routed to another page that looks like this.

You will copy that link from the address bar. Notice I encircled it. That is the link that you need to paste here. and Lastly, Click the launch experiment and take screenshots of the graphics that you see. You can just use the Print Screen button on your keyboard, then open Microsoft paint, you can do it by just typing the word paint after clicking the start button.

Click the paint icon. Then press CTRL + V on your keyboard. Save that file and upload it here.

Please read and review the rules above. I hope this helps.