This guide will show you this can be achieved in a matter of minutes. Keep in mind, username changes can only be done once a month so whatever name you choose, you will have to use it until the next opportunity to change becomes available.
The first step is to go to www.minecraft.net and log in to your Minecraft account.
Once logged in, scroll down until you find "Profile information" and click on "Change".
Enter your new desired Minecraft username and click on "Change Profile Name".
Once this is done, your new Minecraft username will take effect.
Congratulations! You now know How to Change Your Minecraft Username.