Settings for simulating static or rf field between metallic contacts

Hi, I'm a new Comsol user and I'm interested to simulate the 2d field between two electrodes on a substrate. The electrodes can work at low but also at high frequencies. I've been able to draw the metallic contacts on top of the substrate but I don't know how to put a voltage between the two contacts in order to create an electric field between them. Can someone give me an hint?
Thanks