Why am I not given the option to create a new branch?

I’m pretty new to GitHub and have started working through a basic hello-world example. For trying to create a new branch, it said I should be able to type in the name of my branch and an option will appear to create a new branch with that name. However, I’m not given that option. See pic below. How do I create a new branch?

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Do you have push access to the repository you are trying to create the branch within? If not, then you won’t get the option to create a branch in that repository. This is what it looks like if you do have push access: