Here is a summary of duckling care.
https://www.backyardchickens.com/t/750869/raising-and-caring-for-ducklings#post_10611711
And that's what the forum is for - asking questions. I suggest you read the above thread, and then ask additional questions on here.
One thing I would say that is a little different from the above - which I have read and it seems really really good - is I would keep food and water with the ducklings 24/7 for the first two months.
Most duckling raisers get really surprised by the way ducklings play in water. They are waterfowl. They need water. They need it to drink, they need it to wash their heads to prevent serious infections. They develop better with closely supervised time in water up to their bellies at first, and then a little deeper as they grow. They enjoy it. They throw it. They put things in it.
Please look at the suggestions for water management. When you get that handled, life becomes much easier, and more fun.
Another item is diet - if you cannot get duckling starter, and most folks cannot - I urge you to add niacin at 100 mg per gallon to their drinking water. It may even be a good idea to go with B complex, because that contains thiamine, also. From what I have been reading on the forum, those two nutrients are lacking pretty regularly in starter feeding.
That's what I can think of right now.
Welcome to Duckdom!
Oh, and ducklings grow unbelievably quickly. I went through three brooders, because they outgrew the first two.