Horde3D

It's true that I'm just an unexperienced n00b, but You can account on me
utMath optimization work progress is near to end, Just give me some learning resources [pdf and offline prefered], trust me !

I think you may be underestimating the amount of work and experience (little subtle details about the d3d api that only come with experience) that such a port requires, but i wish you the best. It's better to have the ball rolling than to wait for a messiah to port the code. Plus you are young and have time to "waste"

Regarding learning material. It depends on what version of d3d you want to port there are great books for d3d9 and to me it would be the best version to port to since there is abundant hardware that runs d3d9, not so much d3d10. for d3d10 the reference documentation is the best source that i know off.

A decent book about d3d9 is Introduction to 3D Game Programming with Direct X 9.0c: A Shader Approach by Frank Luna, i read it to get familiar with d3d using shaders, however my experience with d3d is limited to the example code of that book (ie toy examples)... for other resources simply search around amazon.com for books or tutorials on-line. Good luck!!!

IMHO it's better to first start with DirectX 9.0c, because only a few of new gpus support DX10. So where should I start from ? [required knowledges and books]

I'd suggest first playing around with the DirextX SDK. There are many samples to study and you don't have to invest any money for books right now. Just google for tutorials for a quick start. You can buy a book, if you really need it, later.
Writing a complete renderer as a first project in DX9 is probably a bad idea. Try writing several demos that represent small parts of the needs of a Horde3D renderer. When you really understand the API of DX9 and the needs of the new renderer you can start writing it.

That's actually the book that was recommended to us on the Uni course I just finished
For something with "Introduction" in the title, it does actually go in a bit deeper than you'd imagine.

As for other documentation, the actual SDK and MSDN areas should give a boost in starting out at the very least

Currently I'm reading the Beginning DirectX 9 by Wendy Jones and documentation that comes with DX SDK seems pretty useless for n00bs.
Beginning DX9 contains subjects such as surfaces, sprites, matrices, texture mapping, 3d lighting, meshes, particle systems and in the end using DInput and DSound.
I'm learning HLSL shaders from ShaderX2 Introduction to HLSL too. After finishing that book I must have a look at DX SDK samples for advanced topics such as HDR lighting, volumetric shadows and ...

But I'm not sure that these books are enough for writing the DX9 backend. BTW, I'll continue reading

All you have to do is get the ball rolling, others will help along the way, this is an open source project, community contributed improvements and patches are the natural path of development.