The first step to printing your own labels in Photoshop is to search for a template. I have found World Label to have an excellent supply of templates (and also the labels themselves if interested).
Go to their website and click on the "CD Labels and Media" link. Here you will be given your choice of templates. If you already have purchased your labels, make sure you pick the right template for your label type.
For my project, I went with WL-OL5025 template. I was able to find labels using this template at my neighborhood Office Depot.

Once you have located the label of your choice, click on the “Click here to view” button.
Now click on the “Download Templates” button.
In the Pre-Configured Templates section, right click on the "Click Here to Download this Template" link and select Save Target As (or Save Link As if using Firefox) and save the template to your computer. Make sure you are saving the PDF version. For some labels, there are multiple versions.
Next, bring up Photoshop.
Click on File/Open and navigate to your PDF and open it.
Select the entire contents of the template and click on Edit/Copy.
Open a new file and select Transparent as your background.
Click on Edit/Paste
Now that you have the template in a new file, you don't have to worry about altering the original template and it can be re-used.
In your Layers palette, lock the layer with the template so you don't alter it in any way.

Position a picture of your choice over one of the place holders for a CD.
When you are ready to print, unlock your template layer and make it invisible so that the lines won't print on your label.
Your finished product might look something like this, but hopefully with people that are easier on the eyes than these guys.
Save your document and Print it. That's it.
You now have the ability to produce custom labels for your CD/DVD collection.
Note: It is important to note that CD labels and DVD labels are not the same. CD labels are usually paper based. When a CD label is used in a DVD player, the heat generated can cause the paper to bubble slightly which could cause the DVD to become unreadable. When labeling DVDs, always use labels that specifically state they are safe for DVD use.