Android "hello world" - versions

Starter question: My "Hello World" attempt won't run, ("No compatible targets were found"), I think this is bacause I selected the latest version for my project (2.2), and the highest AVD version is 2.0.1. Does this make sense? Can I change my project version (haven't been able to find a way to do this), or do I have to 开发者_开发百科start again? If the versions are not backwards compatible, what is the best version to use for the majority of Android devices out there?

Thanks

The suggestion is to use 1.6 as minimum version unless you really need something available only in 2.x. To avoid excessive crowding install only one API set.