x=0:0.1:1; % use colon notation to create a vector from 0 to 1 every 0.1
y=x.^2; % here for example f(x) is a parabola
plot(x,y,'-xg') % specify the a line with 'x' marker and green color '-xg'
xlabel('x'); % label axis with 'xlabel'
ylabel('y');
For more information about plotting use the command 'doc plot'
