Advice on creating an Ant 'Build.xml' file

1. I want to create a new Ant build.xml file

2. The file will need to execute the 'testng.xml' in turn it will execute all my tests/classes nested within the 'pizzas' package.

3. Would anybody please be able to provide me with an ideal build.xml code structure, which will point to the correct directories listed within my current project structure(Image listed below).

4. I have searched online but cant seem to get any build.xml file to work.

Many thanks for your help,