How to Create New Branch on GitHub without using any IDE

Step 1: Go to the file and click on the Edit button as shown in the below image.

Step 2: Then make the required changes in the file and then go to the bottom and click on
Create a new branch for this commit and start a pull request. Learn more about pull requests
and then name your branch and click on “Propose Changes” and a new page will open.

Step 3: Then go to the main page of your project by clicking on Code at top and check all branches by clicking on the button master.
Here you will see your newly created branch. And after moving to that branch you can find the changes done by you.
If you find that you want to merge those changes into the master branch then click on Compare & pull request.

Step 4: Click on Create Pull Request.

Step 5: Click on Merge Pull Request.

Step 6: Click on Confirm merge and you have successfully merged your newly-created branch with your master branch.

Credit : https://www.geeksforgeeks.org/creating-new-branch-on-github-without-using-any-ide/