I just launched a LAMP dropplet from Digital Ocean and am starting coding. When trying to create a new directory inside the web root it says
mkdir: cannot create directory ‘blog’: Permission denied
chown -R user /var/www/html
You have a variety of options on permissions, but essentially
www-data needs read (and probably execute) permission.
For example, you could use
/srv/www/sitename, and then assign permissions
myuser:www-data to it.
There are also numerous threads on the DigitalOcean forums (and around the internet) about permissions schemes for web files. (e.g. Proper Permissions for Web Server Directory.)