The seals now start to be opened, and it does not make comfortable reading. If you come to Revelation looking for some nice easy solution to life's problems or the world's problems then you are going to be disappointed, or you are going to have to utterly misinterpret what it says.
There is a sequence of sevens in Revelation, and within the seven there is a further structure. The first four are about what is happening on the earth, then the next two deal with what happens in heaven, and the final one kind of leads into the next series of visions.
The Lamb opened the first seal and one of the living creatures cried out "come". The first seal released a white horse. He held a bow and a crown and his purpose was to conquer and be a conqueror. As with most things in Revelation there are several lines of interpretation, most of them wrong. Some see this horse as Christ, others as the anti-Christ. Both of these are wrong and do not fit what is happening at all. A third line sees it as a spirit of conquest.
We need to see the vision as a whole, and to see the book as a whole. One of the messages is that all the mayhem and conquest that we see in the world is actually under God's control. Modern man spends a lot of time trying to absolve God of responsibility for various things. This is a most unbiblical approach. If you read the Bible you see that it attributes all sorts of things to God, this is especially evident in the Old Testament. The message is that all the machinations we see going on are actually under God's control and part of His decree.
Now this causes some people a problem. How can a loving God decree wars and famine? Well first of all we need to ask is God Almighty? Answer, yes. If wars and famine are outwith His control then He is not Almighty. So this must be within His control. God has a purpose in all things, Now this does not mean that men do not have responsibility. We are guilty for all our acts of sin.
If we look for a nice neat explanation of how things work out we will be disappointed. How God's decree, man's free will, sin, and God's grace all work together is well beyond our understanding. But we can be certain that God is in full control at all times.