I got SPAM on my computer

At this time I have to receive a site that I really didn't want it every time I open my FireFox the site is
mustangranch.com/?domain=start-digital-media.com
I remind do not visit this link !!!!!!!, at that time I got a nice picture on my computer, and as normal man I click that picture because I want to watch the video. suddenly I have to accept such as usually I install the program, I did not know that program will stay all the time in my computer.
When I checked in my homepage that link is became my home page, even though I have changed the link, the SPAM come again ohh my god I have to format my harddisk I think, because I did not find the program on my control panel and can not remove it.