IP Adress - Cloudflare

I have domain in amen.pt
When I try to update my nameserver … There are requirements for ip adress too…
Anyone can help me how I can update my nameserver… I don`t have the IP adress… Only nameservers from cloudflare…

You can get those name servers’ IP addresses through DNSChecker.org

There are a lot of IP`s in diferente countries. How do i choose the best one for me? Im from Portugal.

Cloudflare uses Anycast. The IP addresses are the same all over the world.