Can I insert hyperlinks in my graphic?

It's not possible to insert a hyperlink within a PNG or JPG image. Instead, you would hyperlink the entire image which would be done outside of Snappa. 

If you create a Facebook Ad for example, the entire image will automatically be hyperlinked. If you're using WordPress, whenever you attach an image, there's a "link to" option under the advanced display settings so you can link the entire image.

Note that no tool will let you insert hyperlinks within an image unless it's a PDF.