I suggest you do some googling to familiarize yourself with a few terms:
Double crankset (or 2x) vs Triple crankset (or 3x)
Chain-guard
Chainring
Crankset.
Also, look at your crankset and see if you can find a model number.
You are getting a bit of advise here from people who are not reading what you have written, and could lead you down the wrong path.