There are four elements in magick: Fire, Water, Air, and Earth. How do you find out what your element is?
The easiest way to discover your element is to look at your astrological Sun sign. The Sun sign is the core of an individual, the overriding nature and will. The twelve zodiac signs are grouped by element. Aries, Leo, and Sagittarius correspond to Fire. Cancer, Scorpio, and Pisces correspond to Water. Libra, Aquarius, and Gemini correspond to Air. Capricorn, Taurus, and Virgo correspond to Earth.
Once you know what element is attributed to your Sun sign, you can begin to explore. Take time to learn everything you can about your element. Dive deep into the correspondences, do meditations, practice magickal rituals focused on that element. Here are a couple suggestions.
One great practice for this purpose is learn which Major Arcana card from the Tarot is associated with your Sun sign, preferably using one of the decks inspired by an occult tradition such as Rider-Waite, Crowley's Thoth deck, or decks from the Golden Dawn or BOTA. Read the source text about the card, research each symbol, contemplate it, and see how the ideas exude in your personality and actions.
Spend time with and pay attention to the physical manifestation of your element. Visit a park or the woods if you're Earth, go swimming if you're Water, build a fire (carefully!) if you're Fire. If you're Air, meditate on your breathing, go to a mountain peak, pay attention to the wind. Gather items that remind you of the physical element and keep them in a place where you will see them regularly.
You can also contact the Elemental appropriate to your element for guidance and understanding of that element. Gnomes govern Earth, Sylphs govern Air, Undines govern Water, and Salamanders govern Fire.
You can do many other things to bring yourself in tune with your element, but these are some basics to get you started. A couple of excellent books packed with many correspondences to the four elements, among other things, are 777 by Aleister Crowley, and The Magician's Companion by Bill Whitcomb. With these books and a little imagination, you'll find other ways to explore the elements. You can also visit the Four Elements section of Asiya's Shadows for meditations and correspondences.