It's my first time to use DAZ 3D, I just wanted to use the files I downloaded here

http://www.sharecg.com/pf/full_uploads.php?pf_user_name=akibabe09&division_id=21&s=dd&pn=2

I think I installed the files correcltly into my DAZ 3d libraries because it appears on my content library, I just have no idea how to use it. Can I apply it to "Genesis" default model? If yes, how? If not, how can i use these files? What is m4/v4 base? been googling it for hours but no luck. Thank you.

No you can't use them on the genesis figures. The base figures are just that ,they have no morphs without buying them. But to use the files you have you will need the free V4 and M4 base figures.

Thank you for your reply, I already have here the Victoria 4 and Victoria 4 Base, but when I apply this poser http://www.sharecg.com/v/55066/view/11/Poser/Heather-Mason-for-v4 to V4 model, only the face change, nothing happened to the hair.

Yes that is just a character morph(face) you will need to add hair separately.You'll figure it out,there are many good tutorials online.  http://www.youtube.com/watch?v=YeG5OeYKawY