How to I animate a tangent line across a sin function?

I am completely new to MATLAB so I'm trying to learn the ropes. Anything I say will most likely sound like it's coming from a child asking what 1+1 is.

Firstly, the graph should look something like this: http://i.imgur.com/09S9AH7.png?1 The tangent line should be animating as it progresses through the x-axis.

Here what my code is:

 %%Clear
 clear;clc;close all

 %%Given

 xstart = -1;

 xend = 3;

 n = 150;

 x = linspace(xstart,xend,n);

 y = x.*sin(x.^2)+1;

 % Plot Animated

 for c = 1:n;

 dy = (x.*(sin(x(c))+(2.*cos(x(c)))))+1-(2.*(cos(x(c)))); % 1st derivative of y

 y2 = (dy.*x(c))+y(1); % Equation of tangent line

 plot(x(c:c+10),y2(c:c+10)) % Animating tangent line

 hold on

 plot(x,y); % sine graph

 plot(x(c),y(c),'o') % Animating ball

 hold off

 axis([-2 4 -2 6])

 pause(0.01)

 drawnow;

 end

I'm not completely sure how to have the tangent line follow along the sin graph line, I have something similar but it is way off.

If you're going to help me can you * explain* how you got the script to work? I don't just want an answer I want to learn how to use MATLAB.