Want to initialize memory from Intel processors

Isn't it here?
Why don't you look into the materials and articles around here and the introductory materials shown in them?

Minimum Steps Necessary to Boot an Intel® Architecture Platform
Minimal Intel Architecture Boot Loader
It's a little off the mark, but the table of contents shows something like this

• Preparation for Memory Initialization........................................................8
  • Processor Microcode Update............................................................................8
  • Processor Initialization............................................................................8
  • Chipset Initialization................................................................................9
• Memory Initialization................................................................................9
  • Technical Resources....................................................................................9
  • MRC Dependencies....................................................................................10
• Post Memory Initialization........................................................................10
  • Memory Test................................................................................11
  • Firmware Shadow................................................................................11
  • Memory Transaction Re-Direction................................................11
  • Stack Setup............................................................................................12
  • Transfer to DRAM....................................................................................12

• Processor Microcode Update............................................................................8
• Processor Initialization............................................................................8
• Chipset Initialization................................................................................9

• Technical Resources....................................................................................9
• MRC Dependencies....................................................................................10

• Memory Test................................................................................11
• Firmware Shadow................................................................................11
• Memory Transaction Re-Direction................................................11
• Stack Setup............................................................................................12
• Transfer to DRAM....................................................................................12

And then there's a StackOverflow article.
Maybe it's close to the big question you have.
How Does BIOS initialize DRAM?

In the response, the relevant document is called the BIOS Writer Guide and is confidential and not leaked.

The document you (and also I) are looking for is called the BIOS Writer Guide and, unfortunatelly, is confidential and has not taken so far (AFAIK).

However, Firmware Support Package has been released continuously, and it says that it also includes a description and (binary) code.
It says that open source developers and developers who can't afford NDA (Non-Disclosure Agreement) can use it, so isn't there any relevant information?

In order to promote their product in the Open Source community, Intel released the Firmware Support Package. This is to be committed akin to a library for the firmware writers and contents (binary) code, the Pillar (PC)ipheral Controller Hub, informally known as "the chipset"), and the CPU1.
An open source developer, or internal any developer that cannot offer to sign an NDA with Intel, can use the FSP to write their own firmware.

Your answers will go on to detail, so you may be able to understand to some extent just by doing so.