There are two judgments that each person will have to face after death.
The first is the particular judgment, which happens immediately. This is the moment when God reveals to us what our eternal life will look like: eternal happiness with him in heaven or eternal punishment in hell.
The second is the last judgment when Jesus returns in glory and we see him seated at God's right hand and coming on the clouds of heaven. (Mark 14:62) This is the moment when creation, as we know it, ceases to exist and he creates a new heaven and a new earth. (Rev. 21:1)
Particular judgment
The Catechism tells us, “each will be rewarded immediately after death in accordance with his works and faith.” (CCC 1021) This moment of particular judgment may sound a little scary to us, and, indeed, I suppose it should. For those who have continually sought to love and serve God and others, the moment will be one of great relief and joy.
Those who have completely been purified of all sin and attachment to sin in this life will enter immediately into heaven. The rest of us go to purgatory to experience the final purification of sin and all attachments it.
It is important to note that God does not judge us in this moment arbitrarily. He does not have a really large silver dollar that he flips the moment we stand before him. He reveals to us what we have already chosen individually in this life. Have we made the choice for God now in time or not? God honors our choice at that moment of particular judgment.
It is very important that a priest be called at the time of one's death. A priest is able to offer the saving power of God's mercy to the dying person, especially to those who have continually turned away from Him in this life. God is generous in offering mercy.
Last judgment
Jesus tells us, “When the Son of Man comes in his glory, and all the angels with him, he will sit upon his glorious throne, and all the nations will be assembled before him. And he will separate them one from another, as a shepherd separates the sheep from the goats. He will place the sheep on his right and the goats on his left.” (Mt. 25:31-33) This moment of the last judgment will be one sight to behold. A number of amazing and glorious things will happen. The resurrection of all the dead will occur and our souls will be reunited with our bodies.
Furthermore, “in the presence of Christ, who is Truth itself, the truth of each man's relationship with God will be laid bare. The Last Judgment will reveal even to its furthest consequences the good each person has done or failed to do during his earthly life.” (CCC 1039) We will see clearly how God was working throughout all of history and in our own lives.
There will be a new heaven and a new earth and the old order will pass away. A complete transformation of the universe will occur and all suffering and sin will be gone as Christ forever establishes himself as King and welcomes us definitively into his happiness. St. Paul tells us in 1 Corinthians 2:9, “...eye has not seen, and ear has not heard, nor has it ever entered the human heart what God has prepared for those who love him.”
Should I be afraid?
The Holy Roman Catholic Church is our sacred home in which Christ dwells for the purpose of saving us from damnation. He comes to us in the sacraments of the Church and in our daily prayers and devotions. He does not abandon us and He is always faithful to His promises, which are revealed through Scripture and tradition. The Holy Roman Catholic Church is God's gift to us and if we remain faithfully at home within her spiritual and physical walls we have nothing to fear at that moment of our judgment.
All saints and angels, pray for us that we may gain our eternal reward!