This part of Paul's letter to the Ephesians tells us to not continue doing things as we did before we committed our lives to Christ. If we continue to do things as before, we have not changed at all, and we may alienate ourselfs from God. It tells us to; no longer live in ignorance; read the Good News which Christ has given to us, and apply it to our daily lifes.
It also tells us not to let anger control us. Paul says, not to let the sun go down with you still angry. For example, if you are having an argument with a friend or family, get to the bottom of the issue, and forgive, or ask for forgiveness. If you can't do this, try not to dwell on it, for that is when the enemy can gain a foothold in your life. Truly, the longer you remain angry at the person, the better chance you have of falling into sin.
He also tells us not to speak evil, of others; as well, do not speak with bitterness. For when we do so, we not only make Christ look bad; we represent him on Earth! We also hurt the other person, which the Lord would never want us to do. For this may turn them away from Christ, and God.
It also tells us to seek righteousness and holiness, for that is what God wants us to do. To doing things the way he would do them, with love, and forgiveness. This means not just saying what you are, but acting on it. Following through on what we have told God we will do, ask him for advice, and when he gives some, follow it.
It is through the love, and mercy of God that we are forgiven, show this same forgiveness to those you know, and even those you don't. Paul says to be kind, to each other, as well as tenderhearted. All these things flow from the Holy spirit witch Jesus gave to us, from the Father. Walk with the spirit and these things are sure to follow you where ever you go.