Sea Foam! You can get it at Auto Zone, Kragen, Pep Boys, etc. - it's in the "fuel additive" section - as for it, I think it comes in a white can. 1/2 can per full tank of fuel, it will probably have a noticeable affect on smoothing your idle.
I also second the chain cleaning and lube, and oil/filter change. Really easy stuff once you learn, and those two things alone will go a long way toward keeping the bike in decent running condition, all other things being equal.
If the bike has the original tires on it, you may ask someone else who has some riding experience to take a look at them, just to see if they are super-hard (tire rubber dries out over time, regardless of usage/wear).
Welcome aboard! Ride safe! Have you taken the MSF class or anything?
-Mark