Highpass is exactly as it sounds. Anything above a preset "Cutoff" frequency will be allowed to continue thru the filter, anything below it will not. It is most commonly used to eliminate any low-end frequencies, and thin out a sound. It's very popular for sizzling lead keyboard sounds. A lot of people use them on vocals to remove rumble or other unwanted low-end material.
Most popular parametric/paragraphic EQs allow to determine how a specific band will act (i.e HPF, LPF, Notch, Shelving etc.). How you would set one up would be dependent on your setup. Are you doing this in hardware or software? What plugins might you be using. There are some good freebie filter plugins out there like Little Duck, and there are plenty of high-end plugins available. But chances are you probably already have what you need. More info would help.