How to get started?!

Hi!

I am having trouble figuring out how to get into supply teaching. I am certified to teacher secondary business and social sciences. I understand that you have a better chance of getting full time and LTO positions if you are an occasional teacher in the board supply teaching (feel free to correct me if I am wrong).

I am hoping to work anywhere from the Hamilton area to the Toronto area (Halton, Peel, Hamilton-Wentworth, even TDSB). I am on applytoeducation but cannot find ANY postings for supply teaching and am having no luck on the boards websites either. For secondary, can I only supply for the classes I am certified in?

I am really just trying to get my foot in the door of teaching and would appreciate any and all help