4 John to the seven churches which are in Asia: Grace be unto you, and peace, from him which is, and which was, and which is to come; and from the seven Spirits which are before his throne;
5 And from Jesus Christ, who is the faithful witness, and the first begotten of the dead, and the prince of the kings of the earth. Unto him that loved us, and washed us from our sins in his own blood,
6 And hath made us kings and priests unto God and his Father; to him be glory and dominion for ever and ever. Amen.
The "seven churches" in verse four are referred to in verses nine through eleven of this chapter as Ephesus, Smyrna, Pergamum, Thyatira, Sardis, Philadelphia, and Laodicea. More information is given at the following link about each one of these seven churches and the state of their congregations at the time Revelation was written: The Seven Churches from Revelations Chapter One.
The author at bibleref.com goes into a bit more detail about what is meant by the phrase 'first begotten of the dead' in reference to Christ in verse five of this passage. Because it was Christ that died by sacrificing his life on the cross to break the power of sin over humanity, we can all rise from our physical death and spend eternity in heaven with Christ if we accept the Salvation he offers us.
If you want to accept salvation from Christ here are some resources
A Prayer for Salvation from Christ:
Lord Jesus, I confess my sins and ask for your forgiveness. Please come into my heart as my Lord and Savior. Take complete control of my life and help me to walk in Your footsteps daily by the power of the Holy Spirit. Thank you Lord for saving me and for answering my prayer.
A more detailed step by step process:
https://www.wikihow.com/Accept-Jesus-Into-Your-Life
