In simple words
Pick the sign you were born under (your Sun sign). If you are not sure, find your birthday in the list of dates.
Each sign has a reading for today, this week and this month. These are general readings for everyone with that sign; for one made from your own full chart, add your birth date.
How these horoscopes are made
Each sign's reading starts from the middle of that sign, where its Sun would sit, and looks at how today's Sun, Moon, Mercury, Venus and Mars meet it: the angles they make, how close they are, and where the Moon is travelling through the sign's houses. New and full moons and planets turning retrograde are added on the days they happen.
Sign horoscopes are general by nature. A personal reading uses your full birth chart, including your Moon and rising sign, and is always more specific. Read these for reflection and fun; your own judgement comes first.