Clock work mod recovery also known as CWM is available for download for the Samsung galaxy Fame GT-S6812. To flash it place in the PDA section of odin and flash.
You can download it from here and ODIN from this post. Find it in the step 3. Do not uncompress the TAR CWM file. Just select PDA in ODIN; connect your phone in download mode and click on Start button to start the flashing process.
After installing Samsung Galaxy Fame CWM Recovery you will be able to flash custom ROMs. You will also need to have a custom clock work mod if you are planning to root your Samsung Galaxy Fame now or in future.