Collision sensor not working?

I need to know how to do this:
create a thin collision pad (Object Type Sensor) under the player, parent it to the player and add the Collision Sensor to that
but i cant figure out what a object type sensor is. Ive searched google for hours:( Can anyone help me? Thanks!

By ‘Object Type Sensor’ do you mean ‘Physics Type Sensor’? Or are you talking about Game Logic sensors? Please try to be a little more specific.