[Q] topic

Hey,guys...I am new to this android development so still learning about it. I am using xperia m c2005 these days. I have unlocked the bootloader of my device and installed CM 11. I didn't installed any custom recovery before flashing it but i had my TA partion backed up before unlocking bootloader. Now i want to return to stock rom 4.3 jellybean. How should i return to stock rom and relock my bootloader? How to wipe out custom rom in order to install stock rom?
This is my first post please reply me in detail. Thnx