Here is a way to get a crude plot of the magnetization as a function of field. Click in the slot of the slider, external field H measured in units of J, to the right of the handle to turn on a magnetic field, and run. Repeat these short runs, increasing the value of the field each time, and you have values of the magnetization plotted for values of the field varying in steps of 10 J.
You can play a similar game with temperature. Click reset over the graph to get a clean slate. Start with the external field equal 1 J, the temperature equal 3.0 J, and run. Now click in the slot of the temperature slider to increase the temperature and run again. Continue and soon you will have a graph of M(T) at fixed H.