"'I am going to bring floodwaters on the earth to destroy all life under the heavens, every creature that has the breath of life in it. Everything on earth will perish. But I will establish my covenant with you, and you will enter the ark - you and your sons and your wife and your sons' wives with you.'" NIV translation
God establishes a covenant (contract) with Noah. He tells him that every living thing on the earth is going to die but, if Noah builds the ark and enters it, he will be saved. This is a contract in that both parties have obligations that bind the other party.
God's instructions to Noah included saving animals to repopulate the earth. In this is a picture of our job as Christians and the way people come to Christ who is our ark. We notice that Noah did not have to chase around after the animals to be saved but instead God brought them to him.
Most of us will not be giving up our homes and moving to another country to be a "missionary" but, like Noah, God will bring people to us that He wants us to lead into the ark of Christ. Our part is in keeping our eyes open for those that God brings to us and showing them the door to the ark.
"'You are to take every kind of food that is to be eaten and store it away as food for you and for them.' Noah did everything just as God commanded him." NIV translation
God also told Noah to gather food for his family and all of the animals. We see that he was obedient in everything that he was told. If he had not obeyed in the details, like the food, the ark would not have done them much good as they would have starved during the coming flood.