*Disclaimer: If this instruction guide doesn't appear to work, it will be deleted*
Alrighty, step 1: go to "youtube.com" and in the search bar search what song you want, click on it.
You see all those red arrows in the picture? With the red box? Well, this is what you copy. To copy, simply right click inside the box. Some sort of drop down thingy (sorry, not very savvy with techical terms) should come and click on the "copy" selection.
Under the "Bio/Summary" box right click again and click the paste button. Don't worry if the "Bio/Summary" thing looks different to what is in the picture, I have found different computers give you different things.
Step 4: Save changes, then go to your little "Welcome: (your penname here)" to see if the video came up. If it didn't, I'm really sorry, but I don't know what's wrong and I don't think I'd be able to help you. Simply alert me that it didn't work and delete the video.