Need to add embed code to Buddypress register page

Hello,

I'm just trying to figure out how I can and this embed code into my register.php page? I want to add it near the top before the signup form but I just can't figure out how to get into the file and change it.

<iframe src="http://www.traffic-zombie.com/en/members/referral?campaignID=398&backgroundColor=%23000&textColor=%23fff" width="100%" height="1100" frameborder="0" style="border: 1px solid #000;"></iframe>

Can someone help?

Thanks
Deborah