This theme is compatible with Bootstrap if you choose to use it in your pages or posts.
Here is a little demo with a code snippet, look at the source to see how the HTML and markdown get tangled.
Hopefully you will find enough information about how to set images in your blog here.
This is an example of a post which includes a feature image specified in the front matter of the post.
The feature image spans the full-width of the page, and is shown with the title on permalink pages:
Jekyll supports the use of Markdown with inline HTML tags which makes it easier to quickly write posts with Jekyll, without having to worry too much about text formatting. A sample of the formatting follows.
This is an example of a post which includes a feature image that has a
text, where you don’t want to redisplay the title.
Mind your image size in order for the text to be displayed where you want it to.
The only limit is your imagination.
