If you want something more flexible you need to get DAZ3d and Zbrush
also, you will need some image editor like photoshop to edit textures.
there is no need to study anything just do what you want and learn in the process. You can ask questions when you don't know something
I have some suggestions how to get started but I will tell that later if necessary.
Onix is right. Both Poser (expensive) and DAZ Studio (free) are great tools and easy to learn if you use their tutorials. I paid $50 for some great tutorials for Poser. I use Photoshop for touching up, particularly getting Gamma and exposure right. Also glad to help if you get into Poser.
Thank you for great advise!
There are lots of things I want to make. It will take some time I can use those well, but I will!!
It is not hard unless you want to do lots of gore and other stuff with mutilated bodies.
So what kind of stuff you want to make?
I guess you may face some problems when you start especially with slow renderings and other similar technical issues but don't rush to change models trying to make it work better as it is often quite easy to fix those problems.