If anyone else stumbles onto this page from google like I did:
use putty (putty.exe) to sign into your server and install curl using this command :
sudo apt-get install php5-curl
Make sure curl is enabled in the php.ini file. For me it’s in /etc/php5/apache2/php.ini,
if you can’t find it, this line might be in /etc/php5/conf.d/curl.ini. Make sure the line :
extension=curl.so
is not commented out
then restart apache, so type this into putty:
sudo /etc/init.d/apache2 restart
Info for install from https://askubuntu.com/questions/9293/how-do-i-install-curl-in-php5, to check if it works this stack overflow might help you: Detect if cURL works?