My Child Is Simply Too Shy. How Can I Make Him Confident?

In reality you cannot 'make' anyone be confident, but you can assist a child to feel confident by making sure that he knows he is loved and that the world and other people are ok .
Sometimes children can pick up on anxieties around them and translate these into shyness or fearfulness.  Or your child may fear rejection, so it is easier just to be shy.
Talk to your child about the world and how things 'don't matter' .  Praise and encourage him to take risks and to step outside his normal comfort zone.  He may only be able to take little steps outside this zone, but make sure that you give him lots of support and encouragement whenever he can overcome his shyness.
Many children also grow out of shyness, so if he is very young, then it may well just be a phase that he is going through.  If he is of school age, it may just be due to the reality of school life, so try not to panic too much, but just give lots of praise and encouragement.