Before beginning the process of contributing a fix or feature, make sure no one has already opened an issue for that feature. If they haven't, you're clear to open your own issue.
Your issue will be used to track conversation on your feature request or bug report. Even if you plan on addressing your issue yourself, please do open one so everybody else knows what you're doing and we can keep conversations manageable. Remember that other people might not have the same solution you do, or might approach the problem differently. What is a bug for you might be a feature for someone else. Use the Issues page to check in for other solutions that might exist, or to follow progress on fixes.
Once you post an issue you want to fix or find an issue nobody else is working on that you have a fix for, for the repo, open a PR, and reference the issue you want to fix in the title of the request so that others are able to tell you're working on it. The managers for this repository reserve the right to close pull requests that have been stale for a long time, or to deny pull requests they can't verify as working and safe.