The following video leads you through making a plot of the spring position x vs. time.

 <iframe width="600" height="450" src="//www.youtube.com/embed/ixSPeMxjODw?rel=0" frameborder="0" allowfullscreen></iframe> 

figure(1); %Create figure #1
clf; %Clear current figure
h=plot( , ,' ');
set(h,'LineWidth',2); %Set linewidth for curve
set(gca,'Box','on','LineWidth',2,...
   'FontName','Helvetica',...
   'FontSize',14); %Set axis properties
xlabel('');
ylabel('');
title('');
axis square; %Make axis box square