This video from the Pinegrow developers is the best introduction you will find to the software and there are plenty more wonderful tutorial videos and comprehensive help files at https://pinegrow.com/support
Once you've watched this and become familiar with Pinegrow's own documentation, flick through these pages for some quick solutions to the difficulties I encountered when I was starting out with this software.
Next: Using Master pages to create a template, to define common content, appearance and behaviour across multiple pages.