3D background on 2D API

[Richie_Mole]

Ok I have figured out how to do this (using isometric type drawings- i beleive its called trimetric, could be wrong) but how would i go about making a virtual world with this?

Graphics2D:

Should i draw lines? rectangles or polygons? I was thinking polygons would be best because you draw them any way you want.

Or

In a .gif format draw the background in a paint program and add it to my game?

---Rich---

P.S.
I have no code for this game at the moment its just in the design mode e.g. MSPaint pics, Paint Shop Pro pics and hand drawn.