You did the right thing by attaching the patch to the tracker issue.
I would be even better if you could turn the patch into a git commit (https://docs.moodle.org/dev/Git_for_developers).
There is a catch 22: Until you have submitted your first patch and had it accepted, you don't have permission to do anything else. Once your first patch is accepted, then you get more tracker permissions, including a 'Submit for peer review' button. If you don't have access to that button, you may be able to add a 'patch' label to the tracker issue, but I just did that.