Mac - How to rename a filename

Method 1,
    -->In Finder, open the folder with your file in it.
    -->See all those pretty icons? Don’t click on them. Find the icon for your file. Click once on that icon then click and hold the mouse button down on the filename below it.
    -->After about a second of holding down the mouse button the text will become editable and you can type over the filename. Be careful you don’t change the extension because bad things will happen!

Method 2,
You can also just select the icon (click once) and then hit the Enter key. That’ll make the file name editable as well.