Presumeably you're using OS X. I assume you're using 10.2.3. Under normal circumstances, simply popping in a blank CD-R prompts the user to name the CD. Once named, the CD-R mounts as a blank volume. It can be renamed, and files can be dragged to/from it just as if it were a hard drive. When you are done copying files to the CD-R, simply click it and drag it to the burn icon. This is a little odd for some people because the trash can turns into the burn icon when you grab a non-yet-written CD-R in the Finder. Anyway, drag the CD-R to the burn icon and that's about that.
In early version of OS X (pre-10.1 I believe) there were problems burning CD-R's. In fact, I'm not sure it could even be done until 10.1, but I can't confirm this.
Hope this helps.