I know what an oil is, but how is it used? I see all these tasty sounding oils and I wanted to know if i can put this in BC. Anyone have any experience with this?

flavored oils (like lorann for example) are fine in buttercreams.
you just add the oils at the same point you would add the extracts.
usually though the oils are much more concentrated and you need less than you would of extracts.

Oils are super concentrated and are generally used in candy making. However, as Diane noted, you can add them to icings and also to cake batter. Just make sure to add only a few drops, though, as a little goes a long way. HTH