mobile

I have seen and confirmed that my device Samsung Galaxy Tab S 8.4 is rooted! Now my friends talk about the Flashing ROM thingi... How can i do it? Do i need to open my computer for it? Does it take much time? Or whatever else.... And does it even get flashed or stuff? Please Please Please tell me how can i do it!

I HAVE ROOTED MY DEVICE THROUGH THE ODIN MODE!!! SO TELL ME THE SUITABLE METHOD!