Putting form code into wordpress for pop up windows

Hi I am trying to create a pop up window in wordpress and have got some code from my total business cart autoresponder and it says this

Paste this code in your web page HTML, just above the </HEAD> tag.

The problem is that I don’t have a </head> tag in my code?

So what I did was put this just above my <h2> tags which was the first thing that was in my code. Was I right in doing this?

Then it says to insert some more code with the following instructions.(script call)

Insert the following line into your page’s BODY tag, immediately before the > character.

However I don’t have a body tag that I can see so I don’t know where to put it?

Lastly it says that I need to put code into my links to stop pop ups occuring when visistors click on linkd within my own site. However I don’t understand whether this is neccessary for me because why would pop ups occur when someone clicks on a link? (I am only wanting my pop up to come up when people enter my site)