Whilst working on my car just before I removed the battery terminal for 5seconds. Totally forgetting bout the brant!

How the fuck do I start my car?! I remember been told a long time ago the procedure to start the car but have totally forgotten.. something bout disconnect the battery then get some one to hold down a button then re connect it then key in ya code or some shit?
Anyways im lost!!! Any help would be greatly appreciated!