This statement of the Wheel of the Year only applies to the Northern Hemisphere. Most of the Sabbats change for the Southern, and I am not familiar enough with the changes to speak about them.
For us the Wheel of the Year begins just after the conclusion of the Samhain Sabbat on or near the 1st of November. The God is ruling in the Summerlands and in the womb of the Goddess at the same time.
The Yule Sabbat is the first of the Sabbats. It is held the day after the Winter Solstice, in other words, the day after the longest night on or around the 22nd of December. The Sun has begun his long return, and the God is born of the Goddess. White, gold, green and red are the traditional colors, holly and greens traditional décor.
Imbolc or Oimelc is held at the beginning of February. The God is still a small infant, so this is the primary celebration of the Goddess on the Wheel, often celebrated as Maiden, Mother and Crone, the Divine Feminine. It is a fire festival of candles, and milk, honey and oatcakes are the traditional foods.
Ostara is the Sabbat of Spring and the childhood of Goddess and God. Held on the Vernal Equinox (March 21or so), it is the time of beginnings, of innocence, of children and sweets and bunnies and eggs in bright colors. Colors for this Sabbat are the bright primary colors, bright green and gold.
Beltane, held on or around the 1st of May, is the time when "A young man's fancy turns lightly to thoughts o' love"! The Goddess and God are young people at this time of the year, with all the randiness that implies. Phallic symbols are traditional for this festival, such as Maypoles. This is also one of the times when the Veil thins and the Fae and Devas become visible to human sight. This fire festival is often celebrated by jumping over a bonfire to bring good health for the year.
Litha is the time of the Heiros Gamos, the sacred Marriage of the Goddess and God. It is celebrated on the Summer Solstice, the longest day (around June 21), and marks the time of the God's greatest power, but paradoxically, the beginning of his long descent into night. It also marks the time when the "God goes into the Grain", when his power turns to making things grow, as the Goddess turns her mind to nurture of all the living. The traditional colors for this Sabbat are rose-pink, gold, silver and grass-green. The traditional drink is mead.
Lughnasadh (pronounced LOO-na-suh) is the primary celebration of the God, the Divine Masculine, on or near the beginning of August. It is sometimes called the Tailltean Games, after the Celtic tradition that Taillte, the Great Earth Mother, after creating the Earth and all that lives in it and on it, lay down her mortal life, and her son Lugh (which means Light) created the games in her honor, the games being the Perseid meteor shower. It is also the first harvest, the grain harvest, and is celebrated with a feast of breads, beer, early fruits and summer vegetables.
Mabon marks the Thanksgiving of the Wheel. It is the time when the greatest part of the harvest is complete, on or near the Autumnal Equinox (around September 22). The God and Goddess are mature or elderly at this point on the Wheel and at the conclusion of the Sabbat, the God departs for the Summerlands, causing the leaves to fall and the cold time of the year to begin. This Sabbat is a true Thanksgiving Feast for the harvest of the previous year. The traditional colors are oranges and reds and browns and deep greens and the foods for the feast should include something of your own making.
Samhain is often called the Witches' Holiday and the Day of the Dead (October 31-November 1). It is still celebrated by dressing up as favorite archetypes, gods and goddesses, skeletons, witches and the like. It is the mourning feast, often featuring both funeral rites for those that have Crossed during this Turn of the Wheel, and an Ancestor Feast. It is another fire festival, including candles, torches, fires in cauldrons and the ubiquitous Halloween Jack o' Lantern! This is the other time of the year when the Veil is thin and we can speak to those on the Other Side.
Samhain also marks the Turn of the Wheel. It is the end of the cycle and the beginning of the next.