I have checked out the code, created a branch and carried out the changes. As I do not have write permissions to the repository I am unable to create a pull requests.
The workflow on GitHub is, that you make a “fork” (that’s like a clone of the repository on your account) and then you can create the pull request from there.
When you look at a project, you can usually just select a file and use the web editor to make changes, which automatically generates you a fork, if you don’t have write access. And from there you can also submit the pull request.
If you already made changes to your local clone of the project, I think it would be easiest if you just copy-paste them over into the editor in the web
You can also have a look at GitHubs forking workflow guide.
When you got the process down, you’ve got your first steps done to contributing more to open source projects!