Just curious, being a junior in High School myself, what is the name of the course (is it AP, standard, honors, etc.)
Ok, now on to your problem:
1. Copeg makes a good point, there is no particular reason for Tester to extend BankAccount. All of BankAccount's variables and methods are public. You may be better off creating a BankAccount object rather than a Tester. However, since this is likely for school, you may be required to make Tester a child of BankAccount so...
2. If you absolutely need Tester to extend BankAccount try making a call to BankAccount's constructor using super Using the Keyword super (The Java™ Tutorials > Learning the Java Language > Interfaces and Inheritance)
That should be enough to get you started