Invalid TLD error when changing nameservers in godaddy

Maybe I am missing basic points, but I have created a droplet in DigitalOcean and followed the excellent guide: The Perfect Server - CentOS 6.4 x86_64 (Apache2, Dovecot, ISPConfig 3)

My domains are on godaddy.com and I want to set new nameservers via "Customizable nameserver settings" - there as instructed by DigitalOcean's tech support I put my droplets IP only to receive "Invalid TLD error"

any idea?

 

You should correct your TLD ( .com / .net - is TLD ), which one are you using ?

 

Where should I update that?
I am using .co (not .com)

 

I am sorry, but I think I miss understood...
I only have the IP address of my server.
how would I be able to point to that IP (in ISPConfig my server name is "s1.example.co")

 

Create a new DNS A record.

s1.example.co -> your IP ( eg. 123.123.213.123 ), this will point the domain to your server.

 

All records not containing errors have been successfully saved to your zone file.
Zone File Record
Host
Status
NS 37.139.xxx.xxx No matching A record found for NS record [s1.example.co]

 

And that's what I mean. You don't have an A record.

 

While this might seem trivial to many, I know that there are many n00bs like myself

Just as a reference to others - Follow the Guide here but read notes that follow:
How To Run Your Own Name Servers With ISPConfig And GoDaddy

1. When you login to your godaddy you will get a new screen, in the Domains Section press the green Launch
2. on the top left corner you have DNS Manager - click it
3. go to Edit Zone under your domain name
4. Delete all records and follow the guide.
5. In your ISPConfig 3, follow the updated guide.