The power of modern personal computers makes 3D finite-element calculations of electric and magnetic fields a practical reality for any scientist or engineer. Rough estimates can be replaced with numerically-exact values for complex geometries and material responses. Tedious benchmarking can be avoided. Despite the benefits, many researchers hesitate to get involved because of the learning curve. Numerical simulations involve insights and a certain degree of art. The author's motivation in developing this course was to share his experience in field calculations with the first-time user. The goal was to build students' knowledge and experience in steps so they could apply finite-element programs confidently. The book emphasize hands-on operation rather than theoretical details.