The hair in your post here is Ali's HR159. It isn't his (or her?) best one for details, others show much finer strands. I'll post one up shortly as an example.
But you can apply the other supplied textures for that hair in the MaterIal room in Poser by clicking on the eye above the texture and going to the drive you have Poser Content installed to and: Content\Runtime\Textures\Ali\Hr-159. Alternatively you can do it in Octane in the Setup window>Materials. Then expand the HR-159 tab, Click the HR159M1 (do the same with M2 and M3 later). Then click Input Texture and at the bottom of the Setup windo click the tab with your current map listed and it will bring up the Select Image File window. Click the Select from file system and it will automatically open up the same location yoour current texture map is in.