As with any technique, there are nuances. But the basic process for using sect is simple. First, find the sect of the chart. This is easy - where's the Sun? If it is above the horizon (the ascendant/descendant axis), it is a diurnal chart that emphasizes the Sun, Jupiter and Saturn. If the Sun is below the horizon, it is a nocturnal chart that emphasizes the Moon, Venus and Mars. Mercury's sect is determined by whether it rises before (oriental) or after (occidental) the Sun.
Next, determine whether or not the planets are in their natural sect. For example, Saturn is a diurnal planet. If it is above the horizon in a diurnal chart, it is matched with its natural sect. This gives Saturn an even extra boost as it delights in its placement. Third, consider whether the planet is in a masculine (diurnal) or feminine (nocturnal) sign.
Planets that are in their natural sect by hemisphere and in a sign which matches their natural sect are in hayz. In Medieval astrology, this was considered a particularly beneficial and powerful condition. If a planet is out of sect by hemisphere, sign or both (a condition Robert Hand calls ex conditione), it will have difficulty expressing positively in the chart.