how to do fourier transform by mathlab

I dont know how to do any transformation like fourier transform on mathlab;.I do use mathlab 7.1

y=fft(x)
x must be 2^n lenght

thanks
what does fft means.
I do not understand" x must be 2^n lenght "

hope you will be kind enough to help me understanding this

can I do inverse fourier transform by mathlab,?

fft = Fast Fourier Transform
x is vector of 2^n (^ means power) places. for example:
n=1, 2^1=2: this vector has 2 numbers
n=2, 2^2=4: this vector has 4 numbers
n=3, 2^3=8: this vector has 8 numbers
n=4, 2^4=16: this vector has 16 numbers
and so on...

Now take vector x in length of 2^n places - it is your information.

Y=fft(x);

this will create Fast Fourier transform to vector x. the results will be in vector Y.
now you can plot this info: plot(y).

you can also do a reverse fft, I think it x=iff(y);

Good luck

Thank you so much sir. It is so kind of you. Can I use this fft for both discrete and continuous time signal?

discrete and continuous are relative things.
for example:
series 1: 0.0001 0.0002 0.0003 0.0004 ... it is a discrete series with delta 0.0001
series 2: 100 200 300 400 ... it is a discrete series with delta 100

if you look at series 2 (that is discrete one) series 1 looks continuous one (but it is also discrete).

thank you once again.