So I'm creating this website and oI was wondering if anyone knew how to make a gallery. I made a section in the site where the images go and I want to have it so when someone goes to it, they see a showcase and when they hover over a picture they want to view a little icon appears (something like a '+') but an image, and when the click it, the image expands and opens like in facebook or any other site when you click an image. Im assuming it has a lot to do with css but if anyone would like to help it would be greatly appreciated. Thank you

This is the main page:

And when you click the arrows it switches the images? Anyways thanks to anyone who helps!

HTML Code:
<img src="" alt="This is the Home page">