And why you want to start with rtlinux if you´re not familiar with linux itself? RTLinux is just a set of patches to include sort of realtime capabilities to the irq handler...
There are many variants of RT implementation available for Linux, all with different advantages, do a little research and choose whichever suits your purpose.
RT Linux is nothing but Linux with real time flavour so it will be better u take the basics of real time and start working on that and If u will ask any perticular question then it will be easy to reply...