Pop-up window appearing on my website

[Moderator note: Please don’t duplicate your thread]

Hi, my demo website meow.site88.net is up and running. I’m hosting my site on 000webhost.com and I’m using the free interface theme, free shoutcast radio player plugin and contact form 7. I’m a newbie and don’t have much experience. Whenever someone visit my site for the first time a pop-up window appear. This problem also appear to persist even after a user has already visited my site on certain browser and device.