Permission denied (SSH_FX_PERMISSION_DENIED: The user does not have sufficient permissions to perform the operation.).

sudo usermod -g www-data [MY USERNAME]
sudo chown -R www-data:www-data /var/www
sudo chmod -R 775 /var/www

scp myfiles.zip myusername@mywebserver.com:

ssh -l myusername mywebserver.com
unzip myfiles.zip
sudo cp myfiles/* /var/www