SSL Certificate confusion.

[Ian]

Hi All,

My client's SSL certificates are about to run out, and we have gone 
through the process of
getting the replacements from Godaddy.  However their instructions as to 
how to use them
are useless.

I expected a .crt and possibly a .key file, and I expected to simply 
replace the existing files
with the new, and restart nginx.

However I have been given two .crt files!  One contains a single 
certificate and the other three certificates!

Is the reason there is no .key file because that is the private key and 
would not be sent out of our control. The old will continue to work fine.

Does anyone know what the group of certificates is for, and how I should 
I introduce them to nginx?

Nginx is a compiled version :-
ian at ianhobson~ $ nginx -V
nginx version: nginx/1.6.0
built by gcc 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
TLS SNI support enabled
configure arguments: --sbin-path=/usr/sbin 
--conf-path=/etc/nginx/nginx.conf --pid-path=/usr/local/nginx/nginx.pid 
--with-http_ssl_module --add-module=../nginx_tcp_proxy_module_v0.4.5 
--add-module=../nginx_http_push_module-0.712

Many thanks

Ian