If you want to try on your phone https://output.jsbin.com/zunupi

Exercise https://jsbin.com/refuyu/edit?html,output

Don't hesitate to look at the documentation for AFrame <a-light> as there are quite a few options.

Note : this is hard. If it gets frustrating after 30min you can just move on. If you manage to get something nice going please do explain how. It's worth a bit of effort though since proper lighting can give a very nice atmosphere to a scene. A good friend of mine once told me that for 3D scenes it's 1 day modeling / 1 day lighting, unfortunately we don't have that luxury today.

Done? Go back to learn more.