Downgrade Samsg Galy Tab 2 7.0 topic

Hello, I want the easy and secure way to downgrade Android 4.2.2 to 4.1.1. I have the original rom, downloaded, but I don't know if Rom manager will work fine, without errors. I have not installed the recovery, the device is rooted only. I don't know if the ROM will work also.... please help me!