To fully use AppleIIGo you need an Apple ][, Apple ][+ or Apple //e ROM image. This ROM image is copyrighted by Apple, and you must be licensed to use it.
If you own an original Apple II you are implicitly licensed to use the software in the ROM of that machine. You do not need to make a copy of your ROM, as ROM files can be found on the Internet.
For your convenience you can find below a related link to the Asimov FTP archive. Under no circumstance should you use any Apple II ROM image if you are not legally entitled to do so.
To install a ROM image in the AppleIIGo Dashboard widget flip to the back side of the widget, click on the ROMs button, and copy your ROM image to the folder that just opened in Finder.
Available ROMs:
* The Apple][Go ROM is a public domain Apple ][ replacement ROM that is capable of running most games not requiring Applesoft. This ROM was written in 2006 by Marc Ressl specifically for use with the Apple][Go Emulator