Ultra stars are anamorphic projection lenses needing double focusing. These lenses are made for projection, so they don't focus very close, usually in the range of around 1.5 to 2 meters or so.
First you mount them to a taking lens (with rear part of anamorphic as close as possible to taking lens as possible) using a clamp or a rail mount. When mounting, you need to rotate and align the anamorphic so that vertical and horisontal lines are really vertical and horisontal. People often shine a light into the lens to see a flare for that alignment. It can work to align it with camera pointed at truly vertical wall too (like a wall, door or something else you know will be aligned).
When focusing an object at around 5 meter or so - first adjust your taking lens to 5 meters and then the anamorphic to 5 meters. If you nail the focal distance on both lenses your image should be in focus. If the focus is wrong on one of the lenses, you won't have anything in focus.
Search in the forums a bit as well and you'll find more threads about:
- aligning different anamorphics
- using double focusing
- Isco Ultra Stars.