Have a look at vectric software. It's very well recommended by DIY cnc'ers and pros alike.

Vcarve pro is probably most popular and best for sign making and you can get a free demo of any of their software here
VCarve Pro

there are free programs such as inkscape and pycam that will generate v-carve profiles and g-code, if you can get your head around them :)

Like I said, you will need to use some kind of software to use your machine ... and it will be VERY frustrating if you get your machine ready to test, and no software to try it with !

Rich