Pentecost is a great day of celebration for Christians! RED is the festival colour for Pentecost.
Pente means 50 in Greek. Does that give you a clue about Pentecost Sunday?

Pentecost comes 50 days after Easter. But the date isn’t nearly as exciting as the events of the very first Pentecost.
On this day, a miracle occurred: tongues of flame lighted on each person...AND each person spoke their own native tongue but, miraculously, everybody understood everybody else!
John 20: 19 - 22

On the evening of that day, the first day of the week, the doors being shut where the disciples were, for fear of the Jews, Jesus came and stood among them and said to them, "Peace be with you."
20 When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord.
21 Jesus said to them again, "Peace be with you. As the Father has sent me, even so I send you."
22 And when he had said this, he breathed on them, and said to them, "Receive the Holy Spirit.

The Holy Spirit was not a wind, but his descent was accompanied with a sound like the blowing of a violent wind.
The Holy Spirit was not fire, but tongues of fire were signs of the fact that the hearts of those present were in fire of the Holy Spirit.

The Holy Spirit was not water, but as well as water fills a vessel the Holy Spirit filled the disciples' hearts.

At Pentecost, the Disciples were empowered by the Spirit to share the Gospel.
Up until then, they had been keeping it to themselves. It is the gift of sharing the Good News boldly, and in such as way as it makes sense to those who hear it. It is not the gift of "speaking in tongues" as some mistakenly think, but the strength to spread the love of God, help the church to grow.

Look at the pinwheel, how can we make it work? Without wind it does not move, with the power of wind it can turn. In the same way, with the power of God’s Holy spirit we are moved to follow in His ways.