i'm back, after successfully adding one of the hairs, so i'll write here how to do this, step by step, as simply as possible (not saying that you can't understand, just trying to make this as simple as i can)
so first of all, you need to unpack the file you have downloaded
in my archive, there were several hair archives, each had a meshes and textures folder
now, if you are going to put it all in the same place, i would suggest making sub-folders for each hair, to make this as simple as you can
so hair one should have:
meshes -> Hair Style -> SKS01 and in this folder, you should have the nif and egm file (this is just my recommendation of a path, you can choose whatever you want, as long as the meshes are in the meshes folder, and the textures are in the textures folder)
and make a similar path for the textures
now, after you have extracted all the hair styles you want to use, it's time to use the CS
first of all, open the CS
in the top of it, click File -> Data
click on the main Oblivion.esm
i will assume that you are not going to use this on a custom race, so for now, this will work on the vanilla races (and you can later do the same for custom races, by also loading the race's esp file, and doing the same changes)
click OK, and make sure that no file is set as Active
now, at the top, click Character -> Hair
in the window you see, right click, and choose New, then give the hair the ID you want
for this tutorial (if you can call it a tutorial) i will use the SKS01 hair
so the ID i'll give it is SKS01Hair
then find this hair in the list, and give it the name SKS01
make sure that Playable and Can Be Female are tagged, while the other two aren't (unless you also want male characters to use this hair)
then click Add Nif, and in the window, go to the path you have set
for now, it will be meshes -> Hair Style -> SKS01
and choose the nif file (it should be the only file you can see)
then click on the Add Image File, go to the path you have created, and choose the normal file (like SKS REN'S 01.dds) make sure that you do not choose a file with an extension (like _hh, _hl or _n)
after that, click OK, and your new hair is done
then you will need to add the hair to the race you want
on the top menu, click Character -> Race
in this window, click on the race you want, and go to the Body Data tab
in the Hair Styles window, just drag and drop your new hair (you will need to have the hair menu open as well)
then, the race you chose now can use the new hair you have made
save this as whatever you want, and you are basically done
do this for all the hairs that you want, and add them to all the races that you want
now, if you want to add the hair to a custom race, you will need to also load the races' plugin, and then add the hair to this race, using the same method
but i would suggest that you first make a plugin that creates all the hairs, and then a plugin that adds them to the races (this could help, but it's up to you to decide)
hope this is simple enough to follow, and will solve this for you
and thanks for this, i finally get to enjoy this hair mod that i always liked