Confusing. I don't understand what this add-on does.

Please also make Awami Nastaliq customizable through this add-on.

This does not work in latest firefox Ubuntu version. The Urdu text on Twitter remains as it is after installing the font

I am pretty sure that this works but I am confused how to it up. I am a computer noob, so i don't know how to setup the user style you mentioned in description. Please help me.