The sky is gray; the clouds are heavy with rain. Rather perfect for Good Friday, I think. Christians throughout the world, will to varying degrees, remember and meditate on the Passion and Crucifixion of Jesus Christ. As a Catholic I am called to fast and abstain from meat today.
When I was a child, I bristled at the thought of calling this Friday "good". What could possibly be good about the death of Jesus? It wasn't until I got older that I understood. His Death, so our sins could be forgiven, before Resurrection. The crown of thorns must proceed the crown of glory. Our Good Friday sorrow turns into Easter Joy, a joy that lasts for all time.
Here are some suggested ways to "celebrate":
2. Watch The Passion of the Christ if you are so inclined. I personally find the movie too focused on the gory violence which speaks to me more of Hollywood than a true respect for Christ's suffering.
3. Attend Good Friday service if your church offers one.
4. Read The Dream of the Rood - a 7th century story of the Crucifixion from the cross' point of view.