what should I do to do so.. if it's an add-on plunging please be kind to put a link.. I found in internet that grid indicator corner text should do the trick but I can't seem to find it anywhere..
You might looking for something like this: GridIndicatorExtraText but that's for WoD (Patch 6.0.2 upwards).
The easiest way is to use my backport of Grid2 r720 for 3.3.5 which provides fully configurable displays (icons, textures/icons, texts and bars) as standard which you can place wherever you want them in the frame.