ShinDokiU

Greetings, fellow modders! First of all, I'm a newbie in modding and editing textures and such; so please explain things as simple as you can. Alright, here is the question: I want to change Serana's default hair with one of the hairstyles I got from Nuska. I've done this before with some other hairs but all of them were just .dds files. However, this one only consists of a single .nif file with two .dds files named "hairlong" and "hairlong_n" (without the quotes, of course). So, can someone please guide me through this if possible? I'd really appreciate it. P.S I have NPC Editor 0.75.1 (but couldn't get it to work on Serana; if needed, I can specify the problem) and also Nifskope. Plus, I'm using Seranaholic, UNP version. Thanks in advance!