the DNS should set to be ns1.yourhost.com
so in your case the required DNS settings would be:
ns1.hostpapa.com
and probably ns2.hostpapa.com if it exists - always good to have at least 2 DNS addresses in there in case the first fails.
It may take up to 24 hours for the change to propagate, but in some cases it will be quicker.
how does pointing the domain to their servers, link with my account too at the hosting site
When you type a domain name into your browser, your computer needs to know the numeric IP address to go to to fetch that site. Every web server has an IP address.
The people who host your site know which of their servers (IPs) host your site but they don't control the data about your domain name.
The people you bought the domain from control the data about your domain, but they don't know which IP it's on.
So you need to tell the people you bought the domain from where the information about the IP address is, they'll then update the authoritative domain record with information about where to find the IP for that domain.
Your webhost provide a domain name server for this purpose (ns1.hostpapa.com in your case).
So you tell the registrar (1and1) to update the domain record with that name server, and when a browser comes along asking for that domain, they look up the name server in the DNS record and find ns1.hostpapa.com. Then they ask ns1.hostpapa.com what the IP address is for yoursite.com, it tells them, because it knows, and then the browser can finally ask that IP for yoursite.com
There are a few levels of caching built in that I'm glossing over, which mean that every time anyone loads any website they don't necessarily have to go back to the root DNS servers to find the IP address, they instead have a locally cached copy, and that's why it can take up to 24 hours for the change to have an effect.
Hope that helps
