Noob Question

[Matt Curcio]

Hi All,
I have just recently installed Octave on Ubuntu 10.4.
I was looking through the manuals and was trying to do something
'easy'  (haha nothing is ever easy!) to start off, just a contour
plot.
I tried to follow a close example but got the inevitable error message:
My little program looks like:
#Surface contour plot:

x = 0:0.1:3;
y = 0:0.1:2;
[X,Y] = meshgrid(x, y);
6-Z=(2*x)+(3*y);
surf(X,Y,Z)

but I get the message:
>error: operator +: nonconformant arguments (op1 is 1x16, op2 is 1x11)

I looked around the web but didn't find exactly what I wanted.  I
guess what I am asking for (among other things)
1) Where is the best place / forum / web address, etc to look for
answers to my future questions/problems?
2) Is there a good guide or set of tutorials that people like?
3) finally any help on this little first attempt of mine??
Cheers,
M