Settings on nikon d3100?

I recently bought a Nikon d3100 and I really enjoy it. However, I was trying to modify some settings in the camera and was getting error messages. Specifically, I wanted to change the picture control and the ISO Sensitivity. However, when I try to choose these from the menu options I get a message saying "This option is not available with current settings" What do I have to change to be able to use these features? This is my first dSLR so any help is appreciated!

1) read the user manual - that is a gold mine of information…

You need to have the camera NOT in the full auto mode. It needs to be in one of the semi automatic modes such as Shutter priority or Aperture priority or full manual. The P program mode will also probably allow you to make some of the changes you want.

You need to spend plenty of time sitting down with the camera and owner's manual and STUDY.