No worries
Network Solutions are just a domain name registrar so if you register domain.com they will let you add forward DNS entries such as
www.domain.com and ftp.domain.com etc.
A PTR record is a reverse DNS entry that maps an IP, say 1.2.3.4 to a forward DNS entry such as
www.domain.com
Because an IP address is typically assigned to a user by their ISP, typically the ISP will look after the reverse DNS entries, so the short answer is that your friend needs to speak to their ISP, assuming they fall into the 99% of people where that's how it'll be setup, and if they're in the other 1% they wouldn't be asking the question.
cheers,
Paul
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paul <at> spamcop.net