Not a programmer for Linux Mint, but I think I can answer some basics;
2. The kernel source code is not in Linux Mint. Linux Mint uses the kernel from Ubuntu or Debian (for LMDE). For the Ubuntu based Linux Mint you can easily get the kernel source code by first enabling the Ubuntu source code repositories (see example steps here viewtopic.php?f=34&t=111839#p626867
, though that topic is unrelated to your question) and then perhaps visit the Ubuntu wiki for compiling your own kernel from source code (https://help.ubuntu.com/community/Kernel/Compile
). That's a good first project, as if you want to develop for the Linux kernel you will be doing that a whole lot
The kernel is developed by the kernel hackers. If you want to contribute to that, head on over to the Kernel Newbies website: http://kernelnewbies.org/
3. GitHub is the source code repository for all the software developed by the Linux Mint developers. Linux Mint developed software is developed as open source, and using GitHub you can fork an existing project with one click (forking means making a copy of the source code, so you can develop changes on your own, which you can submit back [pull request] to the project once you are satisfied with your changes). GitHub has an introduction (http://learn.github.com/p/intro.html
) answering your questions about what and why it is, and a code school (http://try.github.com/
) that will teach you the basics of working with Git and GitHub in 15 minutes: You need to know Git.
4. Helping your questions get answers
If you want to get into Cinnamon, perhaps a good way to start would be to develop your own Cinnamon applet (http://cinnamon-spices.linuxmint.com/applets
). They're all open source, so you can download them and unpack and investigate and try. More applets are always welcomed and valued highly! If you are more confident, visit Cinnamon on GitHub and start looking at the open issues and see if you can reproduce the issue, perhaps event pinpoint the cause, or even submit your first pull request with a fix! Start by forking Cinnamon and compiling and running it, so you are running the development version. Just as with Linux kernel development, you'll be doing that a lot
The Linux Mint developers hang out on IRC at #linuxmint-dev on spotchat.org (open XChat from the menu, then type "/join #linuxmint-dev" to join that channel) and welcome you step in and saying hi
They're busy with the next Linux Mint release, but you'll find also Cinnamon applet developers here and others, and if you have a question usually there is somebody that can help point you in the right direction for further reading.