So, for clarity, I'm going to start dividing the book of Revelation into various sections. I think that sometimes being overly divisive can be harmful, but in taking a hard look at, or a study of, a Biblical text, I would generally call it a good thing. I also think that breaking it into sections can really help you understand what is going on in the book, and what is being implied. For a side note, I like to use the Holman Christian Standard Bible (used here) when possible or the New Oxford Annotated Bible.
Chapters 1-3 are essentially an introduction and a notice to the target audience. John is writing to these churches in Asia (not the modern continent, but more like the modern-day country of Turkey), and he is essentially scolding and commending them for the application of their faith. These churches are Ephesus (good but losing their devotion), Smyrna (good and under persecution), Pergamum (generally good, but has trouble with false or "aberrant" teachings), Thyatira (similar to Pergamum), Sardis (slowly starting to die out), Philadelphia (good/praised), and Laodicea (awful).
Chapters 4-5 are a little bit different and now that we've already moved past the target audience and the introduction we get a little background about who God is and how we can describe him. In chapter 4 we open with the throne room of heaven, and as is typical, God is described kinda strangely through natural phenomena or occurrences. My favorite example of this is the burning bush where God is essentially portrayed through a fire that does not consume (Exodus 3). He is described as "like jasper and carnelian" (Revelation 4:3) which we learned were precious, valuable, and to many, beautiful minerals. We also see this "emerald rainbow [surrounding the throne]" (4:3) which is traditionally seen as a symbol of hope or promise. The throne of heaven should be seen as a promise. As usual, we see recurring use of the word seven. In chapter 5 we are introduced to the lamb (also referred to as the lion of Judah), and he is described as the only one who is worthy or capable of opening the seals (5:5). When we remember the importance of a seal (authenticity and a sort of security), we can see why the ability of the lamb to open the sealed scroll is important.
Okay, so I've put together this small post about the introduction to the book, and I will update soon with the information about the seals and the trumpets as we cover them more. Feel free to comment or to contact me with any questions or concerns you may have!