A uniform electrostatic field points in the +x direction and has a magnitude of E=10 N/C=10 V/m. Find the potential as a function of x, assuming that V=0 at x=0.

Solve for V by knowing that the difference in potential energy is the dot product of the electric field and the infinitesimal path length integrated over the entire path of the particle (from b to a ). Let a be a point in the x=0 plane (where V=0) and let b be and arbitrary positioned point. Once we find the potential at point b we can call this the potential at any point x.
http://www.phys.ufl.edu/~acosta/phy2061/lectures/ElectricPotential.pdf