While in this folder, use the following command to rebuild your document to HTML:
pretext build
Add the --diagrams option if e.g. TikZ images need to be rebuilt as well
(and -v to display updates on the long build process).
pretext -v build --diagrams
To preview your current work:
pretext view
By default your current build is not published publicly. Use this and follow instructions to publish to GitHub Pages:
pretext publish