"Elementary" question, I'm sure...

So, I have the great shot and head shot and I want to "zoom" in one part and blow it up... I have CS4 and LR2... I don't know how to accomplish this. Any help is greatly appreciated!

Also, I apologize for the "elementary-ness" of my question.

Blessings,
M. Riney

If I understand correctly, you probably just need to crop it. You may be able to figure it out yourself (the first step in PS is to type the letter "c" to bring up the crop tool), but if not, Google is your friend.

In LR use the crop tool from the Tool Bar under the histogram in Develop mode. At this point you are worrying only about the shape of the crop box and what's inside it.
Resizing is done later when you export. Check Resize and put in your desired pixel dimensions. And check Output Sharpening also which will adjust the sharpening to the amount of resizing.

Search help in the "Help" section within CS4, lots of info there.