Hi Adrian, welcome to the Linux Mint forums
Thanks for joining the forums!
The source code to Linux Mint developed software is open source, and you can view it here: https://github.com/linuxmint
. Most of the Linux Mint tools are developed with Python, so learning that would be a good start. Knowing your way around GitHub, so you can create forks and contribute patches back, would be a good start. See their 15 minute introduction here: http://try.github.com/
. To get started with development perhaps take it easier and go for a Cinnamon applet? See here the efforts of others, each of which you can download to view the code to see how those were built: http://cinnamon-spices.linuxmint.com/applets
Be sure also to check out the Community
website (tutorials, hardware and software reviews, ideas), and, if you picked the Cinnamon edition, the Cinnamon Spices
website for adding even more themes, applets and extensions to Cinnamon.
You can also chat in real-time with other Linux Mint users. In the Mint Menu, in the Internet section, start the application XChat IRC. You will automatically get connected to #linuxmint-chat for general chat and #linuxmint-help for support with other Linux Mint users.
Have fun with Linux Mint.