hop to apply for staff position?

Everything is written here.

I mean like we have to PM anyone holding that position?

Not every time. For example to become mod you need PM smod and if you want be clan mod you need PM admin etc.. Everything is written on forums, just check.

I am really sorry i am just not able to find it.

If you don't know this stuff nor how to find out more about it, I really wouldn't recommend you to apply at all...

WorldEater gave you the answer, it's all about you bothering to actually read trough.
Also, a good idea would be to actually ask one of the staff members yourself...