Images have many uses:

• Makes your website more appealing
• Breaks up the text
• Can rank in Google Image search
• Adds legitimacy (if it is a pic of your product or people)

Where you get them… there are a number of options

• Steal them (illegal, you could be sued if your site is popular)
• Take your own photos
• Create them, for example using Photoshop
• Use free stock photos
• Use paid stock photos
• Pay a designer/illustrator/photographer

Make them worth sharing – these all have two things in common, words explaining the image, and your website URL:

• A meme
• Something related to current events
• An infographic
• Before/after
• A famous quote

Here are some good resources:

Pixabay – free stock photos, they get commission for any paid photos you buy that also appear in search results