Points on elliptic curves

Hi
I am working with non-supersingular elliptic curves over GF(2^m), with
the general form

y^2 + xy = x^3 + a2 * x^2 + a6

My question is how do you solve for y, for a given x
(There should be a solution, since every polynomial has a square-root
in GF(2^m))
I was thinking along the lines of completing the square, but that
didn't work out.

thanx a lot

.