convert time domain points to frequency points

Hello,

I'm a beginner of MATLAB. I'm having some problems of converting time domain signal into frequency domain.

In time domain, is this the way to plot the graph?

value = [42007935 111212895 184546560 238219725 238219725 184546560 111212895 42007935]; time = [0, 1, 2, 3, 4, 5, 6, 7, 8 ]; plot (time, value);

Could anyone guide me how to plot signal in time domain and frequency domain?