linking image to page with php

Hello!
Can someone point me toward or help me?

I’m not very experienced with php.

I’m using an image in my sidebar that I want to take the user to a specific page. But, I’m building this site so that it can be used on several of my customer’s URL’s. So I wanted to use internal linking as opposed to putting in the full URL with html.

I’m using a featured page widget, but not having luck displaying it properly and I’d rather use code.
I have a plugin that allows php in widgets, but I just cannot find the code anywhere in the codex?

I’ve found this info here LINK but it doesn’t say how to use an image..

thanks in advance for your time!