To solve your equation numerically using one of the ode functions, you set it up as two simultaneous differential equations:
dy(1) = y(2)
dy(2) = y(1)*y(2)
See:
http://www.mathworks.com/help/matlab/ref/ode45.html
for some examples of this.
However, it should be noted that the ordinary methods of calculus can be used to solve this particular differential equation. Its solutions are:
y = 2*a*tan(a*t+b)
y = -2/(t+b)
y = -2*a*coth(a*t+b)
y = b
y = -2*a*tanh(a*t+b)
where a and b are arbitrary constants. (Corrected twice)
