Help pls! baby bird egg, how do I take care of it? Pls!! any help!!?

Its so good and kind of you to try to help the egg to hatch. I commend your effort, but chances are extremely high that it is not a fertile egg. Its true that the parents can often tell that an egg is not "good" so they abandon it. As much as we want to help, the parents have the inside scoop on it. I dont know where you live, but keeping the egg warm was a good thing. According to the temperature where you are the egg might or might not need extra heat during the day. Birds often leave eggs during the day to hunt for food or just rest and the eggs are fine. Keep up your enthusiasm for birds and learn all you can about them. You will find as you learn more about domestic and wild birds you will have many other opportunities to help them survive.