Text on website buttons?

Hi, I've had photoshop cs since it's come out, but I just started using it last week. Anyways, I made a button for my personal website, along with a "header" graphic. Nothing fancy, but I'm wondering how to center text in the middle of a circle I made. For example, I made a circle and want to put a D in it. I've checked lots of websites for info on how to do this, but they don't usually have that basic of an answer.

Thanks in advance,
Mercerdan

Well if your circle is centered in the image, you first have to select the layer (by left clicking on it). Then press CTRL+A, CTRL+X, CTRL+V. You can use this method to center the circle before doing this, too. You have to rasterize the text to do this, though.