1. Get your API details from PayPal proceed to:
PayPal -> Account Settings -> API Access

2. Choose Option 2 - Request API credentials to create your own API username and password.

3. View API Signature.
Copy API Username, Password & Signature

4. Enter Details from step 3 to Settings -> Modules -> PayPal Balance in HostBill:

5. Your PayPal balance will appear on admin Dashboard now