The Bible is a book showing God's character and His love for us. Since He is a Father to us, He wants the best for us. But it would not be very loving of God to let the world be a complete free-for-all because people would get hurt unnecessarily. Therefore God provided rules and laws in the Old Testament by which we should live, and sent Jesus in the New Testament to teach us how to please God, and in doing so please one another as well as ourselves!
There are far too many examples within the Bible of how to live to put them all here. It is always better to read the actual Bible than summaries like this one, but still, here are some of the things which Jesus himself taught about, plus references so you can find them in a Bible and in their full context.
Jesus taught many things but one of his most famous teachings came from the Sermon on the Mount (see Matthew 5). Here he had a large audience who were very new to his teachings. They had never heard anything quite like it! Jesus preached a message of love and happiness. From that came some instructions including:
These instructions bewildered people at the time and still do now, which is why people are so quick to become angry, resentful and unforgiving. It is normal for people to hold grudges against someone who has wronged them in the past and be very unwilling to forgive them. They yearn for revenge and wish ill upon that person in their head even if they can't put it into practice. Jesus was saddened by this kind of attitude because it does not bring about love or happiness at all. It leads to bitterness and resentment.
Instead, when you feel you've been wronged, let it go. If they seek forgiveness, grant it to them and wipe the slate clean. There is no point holding on to old grudges, some of which go back years or even decades! Revenge solves nothing and often makes a situation worse and anger does nothing to sort out the situation either. By loving those who wrong you, you are setting them an example and not becoming worked up by their actions.
Let God sort out your problems instead. Don't forget that God is just as well as loving. This means he is very eager to forgive us, but only if we are happy to forgive others too. If someone has wronged you and are not in the least bit sorry, do not seek to get revenge on them - God will see to it that they are punished if they are unrepentant. God's justice is perfect which is why we should leave the judging to Him. He can see the whole picture and understands motivation as well as actions. This is why it is always better to let God sort out problems than try to sort them out ourselves.
Also on the Sermon on the Mount, Jesus emphasised that we should be storing up our treasures not on earth where they can get damaged and stolen, but in heaven where they are infinitely greater and will never get destroyed and won't get stolen (Matthew 6:19-24). This also keeps us focused on the future and our priorities in the right place. We should be content with what we have and not be a slave to money. You can't serve two masters, money and God. Money can't solve your problems - otherwise the richest people on earth would also be the happiest, which is not the case; in fact often it is the other way round! God, on the other hand, can solve all your problems - for free - and will gladly do so and provide you a place in heaven with far better riches if you just trust in Jesus' words!
Another topic Jesus went into during his Sermon on the Mount was that of worrying (Matthew 6:25-34). We all do it but what does it really achieve? It certainly can't add even a single hour to your life! We as people are often caught up worrying about what to wear, what to eat, what to drink and where our lives are taking us. Jesus offered an alternative to worrying though: pray to God and allow Him to handle all your concerns, then just get on with life safe in the knowledge that God wants the best for us. Jesus illustrates his point with a comparison to the animal kingdom and how they get on with life without stressing out all the time. How much more are we worth and yet God cares deeply about His animals, so how much more will He care about us! Trust Him with your problems then enjoy life!
I once heard it said "we judge others by their behaviour but ourselves by our intentions". How true is that?! Jesus talks about how we should avoid judging others. First of all we can't see the full picture, as the quote above illustrates. Secondly though is that we are often guilty of exactly the same thing ourselves, yet perhaps we phrase it in a different way. You might describe yourself as a person of conviction but accuse someone else of being stubborn. Ultimately they're the same thing. Jesus said that before you criticise others, look at yourself objectively and be honest and say that you do not suffer from the same fault yourself. As Jesus put it - take the plank out of your own eye before you offer to remove a speck from someone else's. Check out this teaching for yourself in Matthew 7:1-6.