Submitting app, new to Git/GitHub

I’m following the steps in the documentation:
I’ve done Step-1: Login to GitHub as popout-apps, located Flathub/flathub, clicked Fork.
Step-2:
$ git clone --branch=new-pr git@github.com:popout-apps/flathub.git
Cloning into ‘flathub’…
Warning: Permanently added the RSA host key for IP address ‘blah-blah’ to the list of known hosts.
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

You need to generate a SSH key locally and add that to your github account. Check out the following tutorial from github:

I have read a tutorial about Git(Hub) and thought I would just have to follow the 6 commands in the documentation!

Flathub is managed through a GitHub project, and app submissions take place as pull requests. To submit an app:

  1. Fork the Flathub repository on GitHub
  2. Clone the fork: git clone --branch=new-pr git@github.com:your_github_username/flathub.git
  3. Create a new branch with your app’s name: git checkout -b your_app_name
  4. Add your app’s manifest to the branch, commit it and push the commit
  5. Open a pull request against the new-pr branch on Github
  6. Your pull request will then be reviewed by the Flathub admins

Looks like the instructions are missing the essential Step-0 “Create SSH Key”. I’ve followed the instructions in your link to do that.
Okay up to Step-4 Add your app’s manifest to the branch, commit it and push the commit
Found this on Stackoverflow:
In order to add files in specific branch follow the below instructions :
To create custom branch
git branch branchname
To switch into custom branch
git checkout branchname
Covered in the instructions
To initialize in the custom branch
git init
To add files in the custom branch
git add file name
To commit the changes made in the custom branch
git commit -m “your message”
Done
To make changes in your GitHub repo
git push

git remote add {myapp} https://github.com/{myaccount}/{myapp}|
git push --set-upstream {myapp} {myapp}|

Click “Compare & pull request”.
Result: There isn’t anything to compare.

Since all this appears to achieve is to send the manifest to the Flathub administrators, I’m not finding this process very rational :(.

I need to understand the basic principle of what I am trying to achieve:
I want to get my manifest onto Flathub. That can’t be done directly though, since only administrators have access to it, because manifests have to be approved.

Therefore I make a fork of the main branch which then exists in my GitHub account and which I do have access to, so I can upload the manifest to that. I then ask the Administrators to check the manifest then if they approve it, to Pull my fork into the main branch. Is that correct?

If so - I have created the Flathub fork. If I now cut and paste the manifest into that in my GitHub account, commit it, then click “Compare & pull request” won’t that achieve what is required?
It appears to work…

Previous post was correct, all that is needed is:

In my repository, make a fork of the main branch which then exists in my GitHub account and which I do have access to, so I can upload the manifest to that. Then make a “Pull Request” which requests the administrators to review it, check it can be built then include it in Flathub.

These https://github.com/flathub/flathub/wiki/App-Submission complicated and incomplete instructions are confusing and unnecessary.