To edit content use prose.io. If you copy-paste tilda content, use tilda-seo.
Every change is published instantly to ttbagroup.github.io
To publish to ttbagroup.com, rebuild the site with npm run build and upload _site folder contents via FTP to public_html. Or just call Dima.
To install dev locally you need jekyll and nodejs. Once installed, run npm start to run local server.