Unable to create external site in aegir ( using barracuda/Octopus )

I have used barracuda/octopus on linode vps: lucid. The instance is on aegir.my-domain.com.
I want to create a different drupal website on / folder or make a new external website.
I have referred this document to create virtual host.
When i did this as below for my vps, and when i restart nginx it gives me this warning:
conflicting server name "mindtrades.com" on 0.0.0.0:80, ignored ( where my domain name is mindtrades)
and it gives me default site under construction .
As i am new to nginx, if somebody can guide me completely step to step, it would be highly appreciated.
Thanks
Vin

Create the following file:

vim /etc/nginx/sites-available/example.com.conf
This file will have the following content: [show file content]

Important: I’ve created a new DNS A RECORD (using GoDaddy’s free Total DNS service) and pointed it to our new server’s IP address. I then change the following line, in the virtual host config file (see above), to reflect the domain name I am using:

3
server_name .yourdomain.com;
If you’ve been following along so far, basically all your virtual host configs will be defined in the /etc/nginx/sites-available directory, to enable a config, you would create a symbolic link (or file shortcut) in the /etc/nginx/sites-enabled directory, equally to disable a config, you would remove the symbolic link. Nginx will do the rest and search the /etc/nginx/sites-enabled directory for active virtual host configs.

Now we will use the /etc/nginx/sites-enabled directory and create a symbolic link to the virtual host config file:

ln -s /etc/nginx/sites-available/example.com.conf /etc/nginx/sites-enabled/example.com.conf
And the final step here is to restart Nginx:

/etc/init.d/nginx restart