To add an image to your profile, add image: and a link to your profile inside the _scholars folder, like this:
---
layout: generic
title: Hector Alfaro
description: Trainer for GitHub
image: https://media.licdn.com/mpr/mpr/shrinknp_200_200/p/7/005/08c/24f/38c031d.jpg
---
Resume: https://githubteacher.github.io/resume/
See how it's done here.