The contents are written in markdown format as described here: https://guides.github.com/features/mastering-markdown/. One can directly edit any file ended with .md using the github UI.
We save pictures in corresponding directories in our Google drive directory, gemadarc. Right click on the picture, select "Get shareable link", copy the link, go to https://github.com/gemadarc/gemadarc.github.io, edit the md file you need to work on, paste the link to the parenthesis as shown below:
![won't work](https://drive.google.com/open?id=0BwM7XYhFgK7odmI0SWo3ZmdwalU)
Change "open" to "uc":
![a working image](https://drive.google.com/uc?id=0BwM7XYhFgK7odmI0SWo3ZmdwalU)
You can click "Preview changes" to see if it works for you. Good luck!
The contents written in markdown format are converted to HTML format by jekyll. The layouts of web pages are defined in files in the _layouts/ directory, which combine files in the _includes/ directory and those .md files.