Four simple steps to get jBilling built from the source:

1. Install the binary version of jBilling and make sure it works by following these instructions
   
2. Install Apache Ant. This is the tool we use to build jBilling. You can download it from here.
   
3. Download the source package of jBilling from here. Unzip the file in the same directory where you installed jBilling in step 1. This will create the directory jbilling/src with all the source files.
   
4. Go to the directory jbilling/src and run 'ant'. This will build and deploy the resulting binaries.
   

Useful links:

• To use the latest source code directly from the repository, follow these instructions.
• To populate your database with sample test data, replace your HSQL files (localDB.*) located in jbilling\server\jbilling\data\hypersonic with these ones from the SVN repository You should have only these two files in you hypersonic directory.
  There are two users in this database: admin and gandalf. Their passwords are '123qwe'.
• Eclipse is a great IDE to work in Java. Learn how to set it up to work with jBilling here