code sign

Hi,
Does anyone knows if adding signature to windows 7 kernel modules still supported by Microsoft?. If yes, what are the procedures, documentations, etc?.

Sure you can, why not?
Not only you can, but in 64 bits editions, you must sign all your drivers for Windows to load them, otherwise you get errors and they won't work (you can relax that limitation, but it constitutes a security issue). 32 bits editions don't enforce that and load any driver without asking.

Here is the official guide to code signing kernel-mode drivers:
Driver Signing - Windows drivers | Microsoft Learn

The link is really good but are there any additional video or something tutorial that puts it in more simpler steps?

There are many tutorials, videos and links, of varying quality around, but you won't get better than the original.

But this prompts me to make this question. What are you wanting to do? Giving the complexities of code signing and specially kernel-mode driver development, "simple steps" are far away from the topic.