$f'(x)=\lim_{h\rightarrow 0}\frac{(3(x+h)-2)-(3(x-h)-2)}{2h}$

Expand the numerator.
Combine like terms.
Factor out an h.
Cancel out the h.
Evaluate the limit h→0.... this is f '(x).

$f'(x)\approx \lim_{h\rightarrow 0.001}=\frac{(3(x+0.001)-2)-(3(x-0.001)-2)}{2(0.001)}=\underline{ \ \ \ \ \ \ \ \ \ \ \ }$

Graph that on your calculator. Also sketch the derivative function you found in part (a). The sketches should look a lot alike.