Hi,
you might try this:
f[x_] := 2 Sin[x] + Cos[3 x]
then
f[Pi/3]
f'[Pi/3]
f''[-Pi/6]
For the plot
Plot[{f[x], f'[x]}, {x, 0, 2 Pi}]
will do the trick. You might want to watch online screencasts such as
http://www.wolfram.com/broadcast/screencasts/handsonstart/
Best wishes,
Marco
