Brain computer Interface (EEG)

I'm Prabakaran Munusamy .Doing Final year project on 'Brainwave pattern recognition' . I'm using Matlab as My platform.I'm a beginner.I already learn to load the file to read the EEG data in Matlab using excel data. I got the graph but in amplitude and time. I need to change the time to frequency.I'm not so sure how to change it to frequency.Is that I need to use FFT.And I try to get the coding but still confusing .Can any one guide me please.I attached the picture of my result...please anyone can guide me..I can learn faster..This coding i just do my self..please check for me..thanks in advance

A=xlsread ('D:\FYP2\EEG DATA\250hz') C3=A(:,1);C4=A(:,2);C5=A(:,3);C6=A(:,4);C7=A(:,5);

AFBM=abs(fft(A)); plot(AFBM)