Where do I insert the code to make an image clickable?

I am having an issue determining exactly how and where to code to make 3 images on my homepage clickable, to link them to another page on the site. The images that I am trying to make clickable are currently being used as background images on a 3_column_HP widget. I have created a CSS transparent block class to overlay in the same spots as the background image of the widget, but here is my problem; I cannot figure out where to put the HTML code of the transparent block.
I’m not a proficient coder so I hope someone who is can help me out. If this description is to vague or you want some more information to help solve this problem, let me know.