Thank you for considering contributing! There are a number of ways you can contribute to this tool.
Open a new issue and suggest something. Anything really, a new feature, a better name for the tool...
When writing a suggestion, make it detailed. If you're suggesting a feature, try to describe the feature in as much detail as you can and also describe the need for this feature. Why do we need this feature?
If you notice that something doesn't work quite right or doesn't do what you expect then open a new issue. Describe detailed steps to reproduce the problem.
Instructions for building the tool are in the README. Once you've made your changes, open a pull request with a detailed description of what you've done.
When playing around in the code, try to match the style of the existing code as best you can. Use spaces (not tabs), curly brackets don't go to the next line, you'll figure it out!