To start this tutorial go ahead and open the image that you will want to know how to change background color in Photoshop. To remove background in Photoshop go over to the tool bar and choose the quick selection tool. Now that the quick selection tool is selected start selecting the part of the image that you would like to keep. Once you have selected some or all of the image that you would like to keep go to the top of the tool bar and click select, inverse. By inversing the selection you will be able know how to erase background in photoshop. Now go to the tool bar and select the eraser tool and start to remove background from image photoshop.
When you start getting close to fine detail sections like the baby hair in the Youtube video you will have to zoom in and start removing background in photoshop by hand.
This is the basic idea of how to delete background in photoshop. I hope this was easy and enjoyable for you.