Each point of an electric field created by multiple dot or sphere charges can be computed as a superposition of the individual electrical force vectors. The individual forces are proportional to the charge value, and inversely proportional to the distance of the charge and the point, squared. Depending on the polatiry, the vector is moving away (positive) or back (negative).
The electrical potential again can be calculated with superposition, except that it’s a scalar value, not a vector one. The set of points which have the same potential, create a equipotential surface. Each force vector is normal to the equipotential surface at the same point.
Note: used d3.js example for hints.