Get Free SSL Certificate & Configure Nginx to use it

• Register on GoGetSSL.
• Choose SSL Certificates -> Domain Validation SSL from top menu.
• On products table click Details button on row Comodo - Free SSL.
• On the opening page click Create New Order button.
• In the Product Configuration section choose: Product Type = SSL Certificates and Select Item = Comodo Trial SSL, then click Complete Order button.
• On the opening page click Incomplete Orders link.
• In the List of all your SSL certificates table click Generate button.
• With Online CSR Generator generate CSR.
• Copy & Paste generated CSR into Paste your CSR text area.
• Then click Validate CSR.
• On the opening page validate your domain via email, dns, http or https.
• In case of validation via email, you will get your private key as post. Do not lost your private key.
• After validation you will get access to Download SSL button on the Manage SSL Certificates page, in the certificate details section.
• Download your certificate & extract it OR check your email, you will get your certificate as archive.
• Assume your domain is mysite.com, then in the archive you will get mysite_com.ca-bundle and mysite_com.crt files.
• Open mysite_com.crt file, copy its content, then open mysite_com.ca-bundle file and paste content to the beginning of the file, save the file.
• Copy files into your domain's folder, for example, into /www/mysite.com/cert/.
• Save your private key as mysite_com.key and download into www/mysite.com/cert/ folder.
• Set nginx configurations:

 server {
    listen 80;
    server_name "mysite.com";
    root /www/mysite.com;
    index index.html;
    location / {
        return 301 https://mysite.com;
    }
}
server {
    listen 443 ssl;
    server_name "mysite.com";
    root /www/mysite.com;
    index index.html;
    ssl on;
    ssl_certificate /www/mysite.com/cert/mysite_com.ca-bundle;
    ssl_certificate_key /www/mysite.com/cert/mysite_com.key;
    # ...
}

References

• You can check SSL of your server with the following tool.
• You can check your certificate with this decoder tool.