Elements are the basic structure of many worship and magical practice. It is the simplest system of correspondences we can find and the less constraint by personal believes. In fact we can find them in western and eastern religions of all kind.
Empedocles was the first Greek who talk about four elements, and Aristotle added a fifth element called Ether, perhaps inspired in the hinduist fifth element Akasha, and later called Spirit or Quintessence by Alchemist.
In some systems, the four element are a derivation of three elements as the mother letters in Kabbalah Aleph , Mem , Shin or the primal elements of alchemy: Mercury, Sulfur and Salt.
The pentagram and the hexagram are symbols of equilibrium between elements. The Earth is an element and also a container for the other three elements so the pentagram or hexagram usually symbolize the Earth as element, planet and physical plane.
The understanding of the elements is a gnosis, and it can be obtained through meditation, visualization and the experience of sensations on the physical world.
In some systems, creatures and nature spirits personify elements. They can be also personified and commanded by Gods and Goddesses.
When starting to relate with elements we can start by the earth to promote stability before starting to work with more dynamic elements.
To relate to earth element:
Visualize yourself rooted in the earth as a tree.
Lie in the earth at your garden or in nature; breathe in and out the energies of the earth into your body through your pores.
Connect with energy of different stones, crystals, food and materials. You can scale them as more or less earthy.
Think about the qualities of heaviness, solidness and stability; relate them to emotions and physical sensations. Find as many correspondences as you can.