just add -R parameter to chown and/or chmod command:
chown -R developer /var/www/html/folder
thats changes everything in the /var/www/html/folder to be owned by developer.
If you want to change group ownership as well, put it after developer and colon:
chown -R developer:new_group /var/www/html/folder
The same thing with permissions:
chmod -R <permission modes> /var/www/html/folder