At the top of each article, just underneath the heading, the name of the principal author of that section appears. If you click on that name, you will be able to send a personal email to him/her directly from the website.
If you want to debate the rectitude or implementation of the methods described, you may post a comment on any page - although you will have to be logged in with a validated email address.
If none of that offers satisfaction, the Contact link at the top right hand corner of your screen will allow you to send a personal email to the project's principal investigator.