Close web site pop-up window

I sure could use assistance:

I am writing Java code to access a particular web site page.

After logging into the site, the IE browser (or the web site) pops-up a little window that requires the user to press <<enter>>. After pressing <<enter>> the site then displays to the requested page.

I am at a loss on how to get the servlet to locate the pop-up screen and then press <<enter>>. (Closing the pop-up window also does the trick.)

I sure could use some help. Thank you in advance.