fatal: Not a valid object name: 'master'.

It is difficult to answer with the information you wrote. The page is private. Please show what the following commands display to you:
git remote -v 
    and
git branch

git remote -v
origin  https://github.com/chalie86/Python.git (fetch)
origin  https://github.com/chalie86/Python.git (push)

C:\paython\django>git branch

C:\paython\django>

its public

How did you creat your C:\paython\django  content? What commands did you use to do that?

The git branch does return some non-empty list of branches -- under normal circumstances.

Well, the repository is public now (it was not -- it wanted the login + password). I have cloned the repository using the command git clone, like this:

e:\__Python\charlie01\ee29184586>git clone https://github.com/chalie86/Python.git
Cloning into 'Python'...
remote: Enumerating objects: 2213, done.
remote: Total 2213 (delta 0), reused 0 (delta 0), pack-reused 2213
Receiving objects: 100% (2213/2213), 69.25 MiB | 1.66 MiB/s, done.
Resolving deltas: 100% (577/577), done.
Updating files: 100% (3611/3611), done.
Receiving objects:  80% (1771/2213), 58.95 MiB | 1.74 MiB/s

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After that I can change the directory to the \Python, and after git branch I get:

e:\__Python\charlie01\ee29184586\Python>git branch
* master

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So, the master branch is definitely there.

i what to add branch django

Try gitk --all to see the structure of the commit points (the history), and then you can decide at what point you want to add the branch. By the way, what is the motivation to add new branch? Is it possible that you confuse the subdirectory with the branch?

what is the diffirence how to create sub directory

am geting
>gitk --all
'gitk' is not recognized as an internal or external command,
operable program or batch file.

If you want to add the subdirectory, just do it. If it is to be part of the same repository, you will just commit new files (in the new subdirectory). It is not related to branches in the sense that you do not need to create a branch to do that.

The gitk is the tool installed as the part of the official Git installation. See https://git-scm.com/ for the installation, and the https://git-scm.com/docs/gitk for the tool documentation. The gitk --all is what you want to use as a beginner. You will see the structure of your repository, including comments added to the commit points. You can also create/delete branch, create a tag, and many other things. It will help you understand how the Git works.