Im new to using fish finders and I am trying to learn to set-up mine and read it, but one of the problems I am having is the depth is not steady when I am anchored, it will jump from like 4.5-6.5 very fast back and fourth how do I fix this.  It is an Humminbird 587ci.

Thats not something that you can really fix.  You're dealing with wave action on the surface causing the boat to go up and down, the swing of the boat at anchor, etc etc.

Turn the sensitivity setting down some.