First you will have to call on the name of Jesus Christ,
In the Bible Eternity is in the book of Revelation chapter 21 and 22.
Eternity is a spiritual place and it is called the New Creation. John 18:36 Eternity is also the kingdom of God.
To find eternity a person have to become a Christian confessing Jesus Christ as Lord and Savior, and reading the Bible and Learning from The Holy Spirit to become a spiritual person so that your spirit can come out of the old creation.
The Old Creation is in the book of Revelation Chapter 2 and 3, when a person is born again as a Christian their spirit-man is some where in one of those 7 Churches realms and from there the spiritual Journey starts towards Eternity the kingdom of God and the New creation.
I hope these Drawing give you some insights and understanding about the spiritual journey from the old creation to the new creation.