Jehovah’s Witnesses have produced volumes of information showcasing our beliefs on this subject.
A brochure that condenses our beliefs on the trinity doctrine is available here.
The forward reads
People often say they believe in the Trinity, yet they differ in their understanding of it.
What, exactly, is the Trinity?
Does the Bible teach it?
Is Jesus Christ the Almighty God and part of the Trinity?
Should You Believe It?
How Is the Trinity Explained?
Is It Clearly a Bible Teaching?
How Did the Trinity Doctrine Develop?
What Does the Bible Say About God and Jesus?
Is God Always Superior to Jesus?
The Holy Spirit—God’s Active Force
What About Trinity “Proof Texts”?
Worship God on His Terms
Under the sub heading “Jesus a Separate Creation” on page 14
Thus, Jesus had an existence in heaven before coming to the earth. But was it as one of the persons in an almighty, eternal triune Godhead? No, for the Bible plainly states that in his prehuman existence, Jesus was a created spirit being, just as angels were spirit beings created by God. Neither the angels nor Jesus had existed before their creation.
Of course this does not mean that Jesus is just another angel. Instead he is the only being directly created by Jehovah God. Every other created thing was created through him. So he is a unique spirit creation with a rank and preeminence over all creation. Jehovah the one uncreated eternal God is the only one Jesus is subject to.
The subject of the nature of God is answered here.