You're on the wrong track. You need to transform the equations you have into a set of equations that clearly define a helix.

Try rotating the coordinate axes clockwise by around the z-axis.

The substitution is:

and of course .

And you'll need to know that a helix is defined by a particle traveling at a constant rate in the z direction, and around a circle with constant angular speed in the x-y direction.

Post again if you're still having trouble.