There are many great resources for Digital Portfolios. This is a list of the ones I used to created this site.
https://www.edutopia.org/blog/e-portfolios-in-the-classroom-mary-beth-hertz
https://sites.google.com/a/edtechteam.com/digital-portfolio/home
http://www.hollyclark.org/2014/03/23/a-beginners-guide-to-creating-digital-portfolios-2/
https://georgecouros.ca/blog/archives/6602
https://learnrichteach.wordpress.com/2017/07/08/a-few-thoughts-on-digital-portfolios/
https://www.eduspire.org/technology-blog-for-teachers/digital-portfolios-in-todays-classrooms/
http://thelearningcounsel.com/article/how-digital-portfolios-improve-teaching
https://www.edtechteam.com/blog/2017/04/google-sites-as-digital-portfolios/
https://mattrenwick.com/publications/digital-portfolios-in-the-classroom/
http://www.hollyclark.org/2017/06/04/5-ways-to-kick-start-reflection-in-your-classroom/
Using Digital Portfolios to Demonstrate Learning
Making a Portfolio on the New Google Sites
Videos
[TRAILER] Digital Portfolios | The Whole Child, The Whole Story
https://www.youtube.com/watch?v=T7FIoQu3Xvo
Digital Portfolios - The Whole Child, The Whole Story
https://www.youtube.com/watch?feature=youtu.be&v=bMbEkNCbVKw&app=desktop
How-To Google Sites Directions