Getting SSL certificate from Gandi is quite straightforward task.
Just remember to combine two downloaded certificates into one
Nginx configuration makes every web browser happy.
ssl on; ssl_certificate /etc/ssl/domain.crt; ssl_certificate_key /etc/ssl/domain.key; ssl_protocols SSLv3 TLSv1; ssl_ciphers HIGH:!ADH:!MD5; ssl_prefer_server_ciphers on;
To check that certificate is installed correctly just go to Qualys SSL Labs site and perform their test. You will get visual interpretation and quite detailed results.