How to create vector symbols

[Con]

First, I would like to say that I am a NEWBIE. I would like to make some new plant symbols (2D) with Adobe Illustrator (or some other vector program). When I design a symbol and import in into vectorworks or copy and past it, then create a symbol, I can't manipulate it like I can when I design it in vectorworks.

If this can be done, could someone walk me through how they create vector symbols outside of Vectorworks?

Thanks

Con