Hi,
Quite simply, you can use the step() and impulse() commands given a continuous-time system. The inputs to these commands is a transfer function generated using the tf(numerator_coeffs, denomenator_coeffs). If you do not specify an output to these functions, they will generate a plot with impulse or step response respectively. If you specify an output, then it is left you to plot the results.
I would encourage you to review the help files for each command, but below is a code snippet to get you going.
transFcn = tf([1], [1,1]) % Transfer function for the system 1/(s+1)
impulse(transFcn); % Generates impulse response
[y, t] = step(transFcn); % Generates response and time
figure(1), clf, plot(t, y), xlabel('Time'), ylabel('Response'), title('Step Response');
Hope this helps!
EDIT: swapped arguments in the plot() fcn call to match axis labels
