Very simple. Just add yourself (can be handmade animation or gif from another source), remove the guy labeled "addplz" (if applicable), and remix! Enjoy! (I'm bad at animation, so I used some sprites I found on google lul) To prevent lots of remixes, if one has been made, remix that one instead.
Music is "Barricade" by Axwell I just found these sprites on Google Images, so I don't know their sources. Feel free to change the music, but leave the old tracks in for others to use.