I want to do distant MBA , But I dont know how to appear in IGNOUMAT and what will be the date for filling that form,

Apart form what Mr Raja has rightly advised, I would add that you keep looking in the weekly employment newspaper (Rojgar samachar) to know about the requisite dates.

MBA and releated management courses admissions in IGNOU is done through IGNOUMAT and it would publish in the beginning of the calendar year.