If you click on the Apple logo in the upper left, then "About This Mac", then "More Info...", it will pull up Apple System Profiler. Click on "Disc Burning" and it will give you information about the drive you have and what types of media it can read from and write to.
Generally the entry-level MacBooks come with only a combo drive, but you can upgrade to the SuperDrive...so it depends on what you purchased.
If you do have a combo drive, then you're stuck. There are CD-Rs larger than 700 MB, but they are very rare and I suspect they wouldn't be compatible since they utilize special techniques to increase the data density.