This would be a quick way to enable HTTPS (SSL) on Apache2.

cd /etc/apache2/sites-enabled
ln -s 001-ssl ../sites-available/default-ssl
nano 001-ssl

Make sure that the vhost configuration is valid. By default it is configured to /var/www. You might want to have some other directory as your document root.

Then run

a2enmod ssl
service apache2 restart

Do leave a comment if you get any errors. Remember to use sudo if you do not have a root shell.