If you dare, you have enough courage to do something. Those who dare are bold and are not afraid. When you feel certain about what you believe, you can use the expression dare say what you think.
Ex: I am so scared of heights that I would never dare to climb a mountain. Just thinking about it makes me feel queasy and nervous!
Ex: Mr. Huckabee told us that we'd fail, but I dare say that after fifteen years in the business, we know a thing or two about how to promote a concert.
If you want to urge someone to do something that the person seems unwilling to do, you can say I dare you, but when someone does something shocking and inappropriate, you might ask, how dare you? to express you are angry about that.
Ex: Originally, I didn't want to go skydiving, but after my husband dared me, I couldn't say no any more. We have an agreement that if either one of us says I dare you to the other, the one who was dared completes the dare.
Bravery means courageous behavior or character. If you are brave, you have courage and are unafraid to do things that seem dangerous or frightening.
Ex: When Tom got his medal, the Chief said he'd never seen such bravery before, and that a medal wasn't nearly enough repayment for running back into that burning building to save that mother and child.
Ex: John's mother was a suspicious person, and quick to get angry. It took a lot of bravery for John to ask her if he could stay up all night to watch the lunar eclipse. Surprisingly, she said yes!
You can say that someone has put on a brave face if they have acted with seeming confidence in a difficult situation. Another way to say the same thing is put up a brave front.
Ex: It's never fun when someone is yelling at you, but Teddy managed to put on a brave face while his dad angrily shouted at him for leaving the front door unlocked when he went out.
Ex: We all knew that our mother was worried about our father's health, but she put up a brave front every time the subject came up, saying that he would get better in time.