You are a Java/Android developer and you want to contribute to Yaaic? Great! :)
There are just two requirements:
Take a look at our github pages: http://github.com/pocmo/Yaaic/
1. Checkout the latest version of Yaaic:
git clone git://github.com/pocmo/Yaaic.git
2. Apply your changes, fix bugs, do whatever you want
3. The world needs your modifications? Okay, test it! Teeeesting :) Code for the official release should be bug free!
4. Create your own branch/account at github, send me a patch or provide some git repository access somewhere else... I'll take a look at your changes and cherry pick them into the master branch :)
5. And finally your changes will be in the next release!
Anything related to Yaaic Development will be published at our github pages: http://github.com/pocmo/Yaaic/