What tool do you use to remove the bonnet

I have just purchased a home that uses well water. In the basement there is a Culligan Mark 2 water softner. I have never used a water softner before and need some help on its proper use. Next to the softner unit is a container for salt. I do not see any in there but there is a lot of orange stuff at the bottom; this container is only filled up about 1/8th of the way with water and it looks as if it has been standing for quite awhile - after running water all through the house this water never changed nor did the unit turn on. The water that comes out of the drains is fairly clear but after it sits for a short the bottom of the glass looks rusted. Any direction on what to do and how to use a water softner would be very helpful. Thanks!