This is actually pretty simple, although the alphabet stew can be confusing to the uninitiated.
So, assuming you're even more of a novice than you probably are, here are the basics:
CD vs DVD: CD is an older technology, and holds about 700MB. A DVD holds about 4.7GB--or about seven times as much as a CD.
Minus (-) vs. Plus (+): These two competing standards for writable DVDs don't really compete with each other anymore. Almost all drives can read and write both standards, and have for many years now. Which kind of disc should you buy? The one on sale. There is no such thing as CD+R.
R vs. RW: Talk about stupid acronyms! The R stands for recordable; the RW stands for rewritable. What that really means is that you can write only once to a CD-R, DVD-R, or DVD+R disc, but you can erase an RW disc and write to it again.
Chances are your drive can handle all of the above. It might also be able to write to Double Layer DVD+R and/or Dual Layer DVD-R discs. These discs hold 8.5GB.
And, of course, there are Blu-Ray drives, but you'd know if you had one of those. They're expensive extras.