So you've made a change to the code/sprites and want to make a Pull Request so it can be added to the game!
Before you do this, though, there are have some requirements so your code doesn't make SS13's infamous spaghetti code problems even worse. Make sure your code fits these requirements or your pull will not be accepted. You may also want to read through the suggestions section.
This has been moved to here: https://github.com/tgstation/tgstation/blob/master/CONTRIBUTING.md