This post is from an earlier year, meaning the information here is likely outdated. You should look for a newer post from the current year to get the newest exercises and notes.
The java simulations that Andreas Görgen showed in the lectures can be found here:
The two first ones allows you to set up charge distributions and visualize fields, field lines and equipotentials. The third one comes with some preconfigured and interesting charge distributions where you can do things such as taking the flux integral of the field. As a recommendation for link 3 try out; setup: charged plate dipole, mouse: surface integral and see how you change the field by varying the the size of the plates. In one limit you get the familiar dipole field, while in the other you get the field from a parallel plate capacitor.