I do not get how to do this problem. Please help 
f(x) = (x+11)squared -6

You did not tell us what the instructions were. So
I can only guess.  In the future, always state the
instructions.

f(x) = a(x - h)² + k

is the graph of a parabola with vertex (h,k), and
its axis of symmetry has equation x = h.  When a
is positive, the parabola looks like a U and when
a is negative, it looks like an upside-down U.

Your problem is

f(x) = 1(x + 11)² - 6

Compare that to:

f(x) = a(x - h)² + k

and you see that a = 1, h = -11 and k = -6

So its graph is a parabola and looks like a U,
since a = 1 is positive.  It's vertex is
(h,k) or (-11, -6) and its axis of symmetry
has equation x = h or x = -11.  Here is its graph:



Notice that the vertex (-11,-6) is its very lowest
point.  So its minimum value is the y-coordinate of
this vertex, or minimum value = -6. Here's its graph
with the axis of symmetry whose equation is x = -11:



Edwin