How/where to change my nameserver settings

[#1]

Hello,
I want to transfer out one of my domains hosted by plusnet to wordpress as it goes over the limit once in a while and plusnet automatically pull all my sites which is a pain.
Plus I've got into WP and it's easier to manage.
I am told I need to change my DNS settings from
plusnet's 195.... numbers
to
ns1.wordpress.com
I have scanned this forum/googled and all the rest but could not find any clear answers where or how to do this.
Do I do it on plusnet or on enom.com who apparently are the registrar of my domain name, though I only found this out yesterday.
I bought my domain over 10 years ago directly from force9, iirc.
There is a plusnet page for: 'Use this page to add custom DNS records to your domain'
but that does not seem to be the same as editing the DNS records - or is it?
thanks for any ideas
C

[#2]

Nameservers point to the host of your DNS.
Nameservers are controlled by the Registrar of the Domain

Quote

I am told I need to change my DNS settings from plusnet's 195.... numbers to ns1.wordpress.com

Not right as 195... numbers is an A record and ns1.wordpress.com is a Nameserver
If you change the Nameserver to Wordpress then they will host your DNS records but you can also change A records to point to Wordpress servers and keep the DNS records with Plusnet

[#3]

thanks, I will persevere with enom.com then
C

[#4]

Information and warnings found at http://en.support.wordpress.com/domain-mapping/map-existing-domain/

Quote

Warning: when you change the name servers, any custom DNS records such as A, CNAME, or MX records will stop working. Specifically, this can mean that any email addresses you have on this domain (such as mail@example.com) may stop working once the mapping is complete. To continue using them, you’ll need to enter new Custom DNS records once you have set up your domain on WordPress.com. We recommend you prepare the relevant information in advance, before you start the domain mapping. Alternatively, you can map to a subdomain, which doesn’t require changing the name servers and will not effect any custom DNS records.

MX records are for email so if you you use this domain for email and change the  Nameservers you could lose emails if you do not prepare in advance.