Github has a simple web interface that makes it very easy to propose a simple change to code. You do not need to install any software or do anything beside register for a git hub account.
1 Identify a change you want to make.
2 Find the file you want to modify on Github
3 Click Edit to open the file
4 Make your change
6 Fill in any additional information in the pull request including a reference to the joomlacode issue.
7 Click Send pull request.
8 Make a note in the joomlacode issue with any a link to the pull request.